| 1 | /* 20jun97/atn: always scaling data up whether dsf is -/+; |
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| 2 | */ |
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| 3 | #include <stdio.h> |
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| 4 | #include <stdlib.h> |
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| 5 | #include <string.h> |
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| 6 | #include <math.h> |
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| 7 | #ifdef XT3_Catamount |
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| 8 | #include <features.h> |
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| 9 | #undef htonl |
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| 10 | #define htonl(x) swap_byte4(x) |
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| 11 | #else |
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| 12 | #include <netinet/in.h> |
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| 13 | #endif |
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| 14 | #include "dprints.h" /* for dprints */ |
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| 15 | #include "gribfuncs.h" /* prototypes */ |
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| 16 | #include "isdb.h" /* WORD_BIT_CNT defn */ |
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| 17 | |
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| 18 | /* |
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| 19 | **************************************************************** |
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| 20 | * A. FUNCTION: pack_spatial |
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| 21 | * pack gridded data values into a bitstream |
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| 22 | * |
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| 23 | * INTERFACE: |
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| 24 | * int pack_spatial (pt_cnt, bit_cnt, pack_null, fbuff, ppbitstream, |
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| 25 | * dec_scl_fctr, BDSlength, errmsg) |
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| 26 | * |
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| 27 | * ARGUMENTS (I=input, O=output, I&O=input and output): |
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| 28 | * (I) long *pt_cnt; count of points in grid |
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| 29 | * (I) long *bit_cnt; count of bits to pack value in. |
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| 30 | * will be calculated if set to zero |
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| 31 | * (I) float *pack_null; parameter value for null (huge number) |
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| 32 | * (I&O) float *fbuff; array containing grid values to pack |
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| 33 | * returned scaled up by Decimal Scale Factor |
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| 34 | * (O) unsigned long **ppbitstream; Null upon entry; |
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| 35 | * returned pointing to new Storage |
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| 36 | * holding packed bitstream; |
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| 37 | * (I) short dec_scl_fctr; decimal scale factor to apply to data |
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| 38 | * (O) long *BDSlength; updated with #bytes in packed bitstream |
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| 39 | * (O) char *errmsg returned filled if error occurred |
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| 40 | * |
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| 41 | * RETURN CODE: |
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| 42 | * 0> success, ppbitstream contains packed values |
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| 43 | * else> error: errmsg holds msg; |
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| 44 | **************************************************************** |
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| 45 | */ |
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| 46 | #if PROTOTYPE_NEEDED |
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| 47 | int pack_spatial ( long *pt_cnt, |
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| 48 | unsigned short *bit_cnt, |
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| 49 | float *pack_null, |
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| 50 | float *fbuff, |
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| 51 | unsigned long **ppbitstream, |
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| 52 | short dec_scl_fctr, |
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| 53 | long *BDSlength, |
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| 54 | char *errmsg) |
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| 55 | |
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| 56 | #else |
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| 57 | int pack_spatial ( pt_cnt, bit_cnt, pack_null, fbuff, ppbitstream, |
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| 58 | dec_scl_fctr, BDSlength, errmsg) |
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| 59 | long *pt_cnt; |
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| 60 | unsigned short *bit_cnt; |
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| 61 | float *pack_null; |
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| 62 | float *fbuff; |
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| 63 | unsigned long **ppbitstream; |
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| 64 | short dec_scl_fctr; |
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| 65 | long *BDSlength; |
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| 66 | char *errmsg; |
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| 67 | #endif |
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| 68 | { |
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| 69 | char *func="pack_spatial"; |
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| 70 | long ipt; /* index over points */ |
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| 71 | int null_flag; /* flag indicating presence of null values */ |
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| 72 | int bit1; /* starting bit in current word */ |
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| 73 | int empty; /* number of empty bits in word */ |
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| 74 | int diff; /* difference of empty - bit1 */ |
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| 75 | long max_value; /* max value storable in bit_cnt bits */ |
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| 76 | unsigned long itemp; /* temporary unsigned integer */ |
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| 77 | unsigned long *bstr; /* pointer running across bitstream */ |
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| 78 | int pack_bit_cnt; /* count of bits to pack parameter values */ |
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| 79 | int unused_bit_cnt; /* count of unused bits for i2 words */ |
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| 80 | /*long byte4_cnt; /- count of bytes using i4 words */ |
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| 81 | long byte2_cnt; /* count of bytes using i2 words */ |
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| 82 | short scl_fctr; /* scaling factor for grid values */ |
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| 83 | double pow_scl; /* 2 ** (-scl_fctr) */ |
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| 84 | double pwr10toD; /* 10 ** (D) */ |
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| 85 | float reference; /* reference = minimum value in grid */ |
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| 86 | float max_grid; /* maximum value in grid */ |
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| 87 | float ftemp; /* temporary float containing grid value */ |
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| 88 | unsigned long *pBitstream; |
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| 89 | unsigned long grib_local_ibm(); |
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| 90 | int wordnum; |
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| 91 | int zero_cnt; |
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| 92 | int prec_too_high = 0; |
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| 93 | unsigned char bdshdr[14]; /* Character array to temporarily hold bds |
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| 94 | * header */ |
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| 95 | int hdrwords; |
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| 96 | |
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| 97 | DPRINT1 ( "Entering %s....\n", func ); |
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| 98 | |
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| 99 | /* |
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| 100 | * |
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| 101 | * A.1 IF (no data in grid) THEN |
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| 102 | * PRINT message |
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| 103 | * RETURN Stat= -1 |
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| 104 | * ENDIF |
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| 105 | */ |
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| 106 | if (*pt_cnt <= 0) { |
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| 107 | DPRINT2 ("%s; invalid pt_cnt = %d\n", func,*pt_cnt); |
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| 108 | sprintf(errmsg, "%s; invalid pt_cnt = %d\n", func,*pt_cnt); |
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| 109 | return (-1); |
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| 110 | } |
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| 111 | |
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| 112 | /* |
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| 113 | * |
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| 114 | * A.2 IF (number of bits to pack into is greater than 30) THEN |
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| 115 | * PRINT message |
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| 116 | * RETURN Stat= -1 |
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| 117 | * ENDIF |
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| 118 | * SET pack_bit_cnt for local use |
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| 119 | */ |
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| 120 | if ( *bit_cnt > 30 ) { |
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| 121 | DPRINT2 ("%s; invalid bit_cnt = %d\n", func,*bit_cnt); |
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| 122 | sprintf(errmsg, "%s; invalid bit_cnt = %d\n", func,*bit_cnt); |
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| 123 | return (-1); |
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| 124 | } |
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| 125 | pack_bit_cnt = (int) *bit_cnt; |
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| 126 | DPRINT1 (" use Pack_bit_cnt= %d\n", pack_bit_cnt); |
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| 127 | |
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| 128 | /* |
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| 129 | * |
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| 130 | * A.3 FOR (each data point) DO |
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| 131 | * SCALE all values of data array !multiply by 10**DSF |
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| 132 | * ENDDO |
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| 133 | */ |
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| 134 | pwr10toD= pow ( 10., (double) dec_scl_fctr ); |
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| 135 | for (ipt=0; ipt < *pt_cnt; ipt++) fbuff[ipt] *= pwr10toD; |
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| 136 | |
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| 137 | DPRINT2 (" Decimal Scale Fctr= %d, scale data by 10**dsf "\ |
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| 138 | "(Fbuff *= %lf)\n", dec_scl_fctr, pwr10toD); |
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| 139 | /* |
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| 140 | * |
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| 141 | * A.4 INIT reference, max_grid, null_flag |
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| 142 | */ |
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| 143 | reference = 1.e30; |
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| 144 | max_grid = -1.e30; |
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| 145 | null_flag = 0; |
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| 146 | |
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| 147 | /* |
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| 148 | * |
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| 149 | * A.5 FOR (each data point) DO |
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| 150 | * IF (value < reference) THEN |
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| 151 | * SET reference to this value !smallest value |
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| 152 | * ENDIF |
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| 153 | * IF (value > max_grid AND not a missing value ) THEN |
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| 154 | * SET max_grid to this value !largest value |
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| 155 | * ENDIF |
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| 156 | * IF (value >= missing value ) THEN |
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| 157 | * SET null_flag to 1 !grid contains nulls |
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| 158 | * ENDIF |
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| 159 | * ENDDO |
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| 160 | Find reference (minimum) and maximum values of the grid points |
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| 161 | */ |
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| 162 | for (ipt = 0; ipt < *pt_cnt; ipt++) { |
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| 163 | ftemp = *(fbuff+ipt); |
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| 164 | if (ftemp < reference) reference = ftemp; /* REF is SCALED UP */ |
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| 165 | if (ftemp > max_grid && ftemp < *pack_null) max_grid = ftemp; |
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| 166 | if (ftemp >= *pack_null) null_flag = 1; |
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| 167 | } |
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| 168 | |
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| 169 | DPRINT2 (" Max before taking out Ref =%.4lf\n Null flag=%d\n", |
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| 170 | max_grid, null_flag); |
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| 171 | |
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| 172 | /* Compute maximum range of grid (max_grid - reference) */ |
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| 173 | /* |
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| 174 | * |
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| 175 | * A.6 IF (max value is same as smallest value AND |
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| 176 | * null_flag is zero) THEN |
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| 177 | * CLEAR pack_bit_cnt !constant values, no nulls |
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| 178 | * CLEAR max_grid !set grid range to 0 |
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| 179 | */ |
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| 180 | if (((max_grid - reference) < 1.0) && null_flag == 0) { |
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| 181 | pack_bit_cnt = 0; |
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| 182 | max_grid = 0; |
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| 183 | |
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| 184 | /* |
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| 185 | * A.6.a ELSE IF (max value is same as smallest value AND |
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| 186 | * null_flag is set) THEN |
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| 187 | * SET max_grid to 1 !const values, some nulls |
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| 188 | */ |
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| 189 | } else if (((max_grid - reference) < 1.0) && null_flag == 1) { |
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| 190 | max_grid = 1.; |
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| 191 | |
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| 192 | /* |
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| 193 | * A.6.b ELSE IF (max value <= -1.e29 AND null_flag is set) THEN |
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| 194 | * PRINT message |
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| 195 | * RETURN Stat= -1 |
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| 196 | */ |
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| 197 | } else if (max_grid <= -1.e29 && null_flag == 1) { |
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| 198 | DPRINT1 ("%s; Grid contains all NULLS\n",func); |
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| 199 | sprintf(errmsg, "%s; Grid contains all NULLS\n",func); |
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| 200 | return (-1); |
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| 201 | |
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| 202 | /* |
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| 203 | * A.6.c ELSE IF (max value not equal to reference) THEN |
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| 204 | * SET max_grid (max_grid-reference) !non-constant values w/wo nulls |
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| 205 | */ |
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| 206 | } else if (max_grid != reference) { |
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| 207 | max_grid -= reference; |
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| 208 | |
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| 209 | /* |
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| 210 | * A.6 ENDIF |
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| 211 | */ |
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| 212 | } |
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| 213 | |
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| 214 | /* |
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| 215 | * |
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| 216 | * A.7 DEBUG print grid range and reference value |
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| 217 | */ |
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| 218 | DPRINT2 ( " Reference = %f\n Max_grid (range) = %f\n", |
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| 219 | reference, max_grid); |
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| 220 | |
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| 221 | /* Find minimum number of bits to pack data */ |
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| 222 | /* |
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| 223 | * |
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| 224 | * A.8.a IF (grid range is not zero) THEN |
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| 225 | */ |
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| 226 | if ( max_grid != 0 ) |
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| 227 | { |
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| 228 | |
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| 229 | /* |
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| 230 | * |
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| 231 | * A.8.a.1 DEBUG print input bit width |
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| 232 | * IF (input bit_num is zero) THEN |
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| 233 | * CALCULATE number of bits needed to store grid range |
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| 234 | * DEBUG print calculated bit count |
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| 235 | * ENDIF |
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| 236 | */ |
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| 237 | DPRINT1 ( " Input bit cnt = %d\n", pack_bit_cnt ); |
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| 238 | if ( pack_bit_cnt == 0 ) |
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| 239 | { |
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| 240 | pack_bit_cnt = (int)(floor(log10((double)max_grid) / log10(2.)) +1); |
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| 241 | DPRINT1 ( " Calculated bit cnt = %d\n", pack_bit_cnt ); |
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| 242 | } |
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| 243 | if ( (pack_bit_cnt < 0) || (pack_bit_cnt > 30) ) |
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| 244 | { |
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| 245 | DPRINT1 ("%s: Calculated bit count OUT OF RANGE [0 - 30] !!\n", func); |
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| 246 | sprintf (errmsg, "%s: Calculated bit count OUT OF RANGE!! bit_cnt: %d max: %f\n", func,pack_bit_cnt,max_grid); |
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| 247 | return (-1); |
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| 248 | } |
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| 249 | /* |
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| 250 | * |
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| 251 | * A.8.a.2 CALCULATE various byte counters |
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| 252 | * !itemp: #bits required for header + grid |
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| 253 | * !Byte2_cnt: #bytes rounded up to next 2-byte bdry |
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| 254 | * !Byte4_cnt: #bytes rounded up to next 4-byte bdry |
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| 255 | * !Unused_bit_cnt: #unused bits at end using byte2_cnt |
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| 256 | * DEBUG print expected length and unused bits |
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| 257 | */ |
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| 258 | itemp = *pt_cnt * pack_bit_cnt + 11 * BYTE_BIT_CNT; |
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| 259 | byte2_cnt = (long) ceil(((double) itemp / BYTE_BIT_CNT) / 2.) * 2; |
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| 260 | /*byte4_cnt = (long) ceil(((double) itemp / BYTE_BIT_CNT) / 4.) * 4;*/ |
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| 261 | unused_bit_cnt = byte2_cnt * BYTE_BIT_CNT - itemp; |
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| 262 | DPRINT1 ( " Calculated length = %ld bytes (Rnd2)\n", byte2_cnt); |
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| 263 | DPRINT1 ( " Bitstream padding = %ld bits\n",unused_bit_cnt); |
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| 264 | |
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| 265 | /* |
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| 266 | * |
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| 267 | * A.8.a.3 CALCULATE maximum storable value |
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| 268 | * CALCULATE scl_fctr required to fit grid range |
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| 269 | * into available bit width |
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| 270 | */ |
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| 271 | max_value = (long) pow(2., (double) pack_bit_cnt) - 1; |
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| 272 | if (max_value < 2) max_value = 2; |
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| 273 | scl_fctr = -(short) floor(log10((double) (max_value-1) / |
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| 274 | (double) max_grid) / log10(2.)); |
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| 275 | pow_scl = pow(2., (double) -scl_fctr); |
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| 276 | DPRINT1 ( " Calculated Binary scale = %d\n",scl_fctr); |
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| 277 | } |
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| 278 | |
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| 279 | /* |
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| 280 | * |
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| 281 | * A.8.b ELSE !max_grid = 0, all zero data or constant values |
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| 282 | * SET number of bits to pack to zero |
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| 283 | * SET lengths to 12 bytes |
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| 284 | * SET unused bits to 8 (1 byte of padding) |
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| 285 | * SET scl_fctr to 0 |
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| 286 | * DEBUG print constant grid |
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| 287 | * ENDIF |
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| 288 | */ |
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| 289 | else |
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| 290 | { |
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| 291 | pack_bit_cnt = 0; |
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| 292 | byte2_cnt = 12; |
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| 293 | /*byte4_cnt = 12;*/ |
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| 294 | unused_bit_cnt = 8; |
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| 295 | scl_fctr = 0; |
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| 296 | DPRINT0 ( " Constant grid. Using bit cnt = 0\n"); |
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| 297 | } |
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| 298 | |
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| 299 | /* |
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| 300 | * |
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| 301 | * A.9 MALLOC space for bitstream (Rnd2_cnt) |
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| 302 | * IF (failed) THEN |
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| 303 | * PRINT error mesg |
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| 304 | * RETURN Stat= 999; |
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| 305 | * ENDIF |
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| 306 | */ |
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| 307 | pBitstream = ( unsigned long * ) malloc ( sizeof( unsigned long ) * |
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| 308 | byte2_cnt ); |
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| 309 | if ( !pBitstream ) |
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| 310 | { |
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| 311 | DPRINT1 ("%s: MAlloc failed pBitstream\n", func ); |
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| 312 | sprintf(errmsg, "%s: MAlloc failed pBitstream\n", func ); |
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| 313 | return (999); |
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| 314 | } |
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| 315 | |
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| 316 | /* |
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| 317 | * |
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| 318 | * A.10 SET ptr to bitstream |
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| 319 | * UPDATE bit_cnt for input structure |
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| 320 | */ |
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| 321 | *bit_cnt = (unsigned short) pack_bit_cnt; |
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| 322 | DPRINT1 (" Updated input bit cnt to %d\n", *bit_cnt); |
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| 323 | bstr = pBitstream; |
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| 324 | |
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| 325 | /* |
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| 326 | * |
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| 327 | * A.11 ZERO out entire bitstream |
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| 328 | */ |
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| 329 | zero_cnt = ceil(byte2_cnt / (float)sizeof(long)) * sizeof(long); |
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| 330 | memset ((void *)pBitstream, '\0', zero_cnt); |
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| 331 | |
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| 332 | /* |
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| 333 | * |
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| 334 | * A.12 PUT packing info into first 11 bytes: |
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| 335 | * NOTE: The Table 11 Flag stored in the first |
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| 336 | * 4 bits of Octet 4 is HARDCODED to 0000. |
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| 337 | * This implies Simple packing of float |
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| 338 | * grid point data with no additional flags. |
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| 339 | * Octet 1-3 = Byte2_cnt |
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| 340 | * Octet 4 = Table 11 Flag & unused_bit_cnt |
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| 341 | * Octet 5-6 = Scl_fctr |
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| 342 | * Octet 7-10 = Reference truncated to DSF precision |
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| 343 | * Octet 11 = Pack_bit_cnt |
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| 344 | * Octet 12 = Bitstream starts (bit 25 of word 3) |
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| 345 | */ |
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| 346 | |
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| 347 | |
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| 348 | set_bytes_u(byte2_cnt, 3, bdshdr); |
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| 349 | |
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| 350 | itemp = unused_bit_cnt; |
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| 351 | set_bytes_u(itemp, 1, bdshdr+3); |
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| 352 | |
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| 353 | set_bytes_u(scl_fctr, 2, bdshdr+4); |
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| 354 | |
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| 355 | DPRINT1 (" Reference (%f) ", reference); |
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| 356 | reference = floor((double) reference + .5); |
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| 357 | DPRINT1 ("truncated to DSF precision= %lf\n", reference); |
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| 358 | itemp = grib_local_ibm(reference); |
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| 359 | DPRINT1 (" Reference converted to local IBM format= 0x%x\n", itemp); |
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| 360 | |
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| 361 | set_bytes_u(itemp, 4, bdshdr+6); |
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| 362 | |
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| 363 | set_bytes_u(pack_bit_cnt, 1, bdshdr+10); |
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| 364 | |
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| 365 | bit1 = 25; |
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| 366 | |
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| 367 | memcpy(bstr,bdshdr,11); |
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| 368 | |
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| 369 | /* |
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| 370 | * For non-internet byte order machines (i.e., linux), |
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| 371 | * We reverse the order of the last byte in the bds header, since |
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| 372 | * it will be reversed once again below. |
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| 373 | */ |
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| 374 | hdrwords = 11/(WORD_BIT_CNT/BYTE_BIT_CNT); |
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| 375 | set_bytes_u(bstr[hdrwords], WORD_BIT_CNT/BYTE_BIT_CNT, |
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| 376 | (char *)(bstr+hdrwords) ); |
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| 377 | |
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| 378 | bstr += hdrwords; |
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| 379 | |
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| 380 | |
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| 381 | /* |
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| 382 | itemp = unused_bit_cnt; |
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| 383 | *bstr = (byte2_cnt << 8) | itemp; |
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| 384 | bstr++; |
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| 385 | *bstr = scl_fctr; |
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| 386 | |
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| 387 | DPRINT1 (" Reference (%f) ", reference); |
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| 388 | reference = floor((double) reference + .5); |
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| 389 | DPRINT1 ("truncated to DSF precision= %lf\n", reference); |
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| 390 | itemp = grib_local_ibm(reference); |
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| 391 | DPRINT1 (" Reference converted to local IBM format= 0x%x\n", itemp); |
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| 392 | |
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| 393 | *bstr = (*bstr << 16) | (itemp >> 16); |
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| 394 | bstr++; |
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| 395 | *bstr = (itemp << 16) | (pack_bit_cnt << 8); |
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| 396 | bit1 = 25; */ /* starting bit within current bstr word */ |
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| 397 | |
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| 398 | /* |
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| 399 | * |
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| 400 | * A.13 IF (grid values are not constant) THEN |
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| 401 | */ |
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| 402 | if (pack_bit_cnt > 0) { |
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| 403 | |
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| 404 | |
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| 405 | /* |
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| 406 | * A.13.1 SET empty value |
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| 407 | */ |
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| 408 | empty = WORD_BIT_CNT - pack_bit_cnt + 1; |
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| 409 | |
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| 410 | for (ipt=0; ipt < 5; ipt++) DPRINT4 ( |
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| 411 | " ITEMP= (*(fbuff+ipt) - reference) * pow_scl + .5=\n"\ |
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| 412 | " (%lf -%lf) * %lf + .5 = %lf\n", |
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| 413 | *(fbuff+ipt), reference, pow_scl, |
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| 414 | (*(fbuff+ipt) - reference) * pow_scl + .5); |
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| 415 | |
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| 416 | /* |
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| 417 | * A.13.2 FOR (each point in bitstream) DO |
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| 418 | */ |
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| 419 | for (ipt = 0; ipt < *pt_cnt; ipt++) { |
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| 420 | |
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| 421 | /* |
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| 422 | * A.13.2.1 IF ( data value < pack_null) THEN |
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| 423 | * SET itemp to (value - reference) * pow_scl + .5; |
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| 424 | * ELSE |
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| 425 | * SET itemp to max value; |
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| 426 | * ENDIF |
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| 427 | */ |
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| 428 | if (*(fbuff+ipt) < *pack_null) { |
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| 429 | itemp = (*(fbuff+ipt) - reference) * pow_scl + .5; |
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| 430 | } else { |
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| 431 | itemp = max_value; |
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| 432 | DPRINT1 ("%s: Setting to max_value: Precision may be too high !!\n", func); |
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| 433 | sprintf (errmsg, "%s: Setting grid point to max value, precision may be too high", func); |
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| 434 | /* return (-1); */ |
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| 435 | } |
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| 436 | |
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| 437 | /* |
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| 438 | * A.13.2.2 COMPUTE if data point can fit in current word |
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| 439 | */ |
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| 440 | diff = empty - bit1; |
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| 441 | |
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| 442 | /* |
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| 443 | * A.13.2.3.a IF (data point falls within word ) THEN |
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| 444 | * SHIFT value to the correct bit position |
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| 445 | * COMBINE it with data in current word of bitstream |
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| 446 | * CALCULATE starting bit in curr word for next time |
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| 447 | */ |
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| 448 | if (diff > 0) |
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| 449 | { |
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| 450 | *bstr |= itemp << diff; |
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| 451 | bit1 += pack_bit_cnt; |
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| 452 | } |
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| 453 | |
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| 454 | /* |
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| 455 | * A.13.2.3.b ELSE IF (data point ends at word boundary) THEN |
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| 456 | * COMBINE value with data in current word of bitstream |
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| 457 | * SET starting bit to 1 |
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| 458 | * BUMP word counter in bitstream up by 1 word |
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| 459 | */ |
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| 460 | else if (diff == 0) |
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| 461 | { |
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| 462 | *bstr |= itemp; |
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| 463 | bit1 = 1; |
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| 464 | bstr++; |
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| 465 | } |
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| 466 | |
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| 467 | /* |
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| 468 | * A.13.2.3.c ELSE !point crosses word boundary |
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| 469 | * STORE "diff" bits of value in current word of bitstream |
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| 470 | * BUMP word counter in bitstream up by 1 word |
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| 471 | * STORE remaining bits of value in next word |
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| 472 | * CALCULATE starting bit in curr word for next time |
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| 473 | * ENDIF !word location check |
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| 474 | */ |
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| 475 | else /* pixel crosses word boundary */ |
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| 476 | { |
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| 477 | *bstr |= itemp >> -diff; |
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| 478 | bstr++; |
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| 479 | *bstr |= itemp << (WORD_BIT_CNT + diff); |
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| 480 | bit1 = -diff + 1; |
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| 481 | } |
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| 482 | |
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| 483 | /* |
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| 484 | * A.13.2 ENDFOR loop over grid points |
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| 485 | */ |
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| 486 | } |
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| 487 | |
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| 488 | /* |
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| 489 | * A.13 ENDIF (pack_bit_cnt > 0) |
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| 490 | */ |
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| 491 | } |
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| 492 | |
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| 493 | /* For little endian machines, swap the bytes in the bstr pointer */ |
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| 494 | /* for (wordnum = 0; */ |
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| 495 | for (wordnum = hdrwords; |
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| 496 | wordnum < ceil(byte2_cnt/(float)(WORD_BIT_CNT/BYTE_BIT_CNT)); |
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| 497 | wordnum++) { |
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| 498 | set_bytes_u(pBitstream[wordnum], WORD_BIT_CNT/BYTE_BIT_CNT, |
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| 499 | (char *)(pBitstream+wordnum) ); |
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| 500 | } |
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| 501 | |
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| 502 | /* |
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| 503 | * |
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| 504 | * A.14 ASSIGN bitstream block to ppbitstream pointer |
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| 505 | * SET BDSlength (size rnded to next 2 byte boundary) |
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| 506 | * RETURN Status 0 ! success |
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| 507 | */ |
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| 508 | *ppbitstream = pBitstream; |
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| 509 | *BDSlength = (long) byte2_cnt; |
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| 510 | |
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| 511 | DPRINT1 ("Exiting pack_spatial, BDS len=%ld, Status=0\n" , *BDSlength); |
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| 512 | |
|---|
| 513 | if (prec_too_high) { |
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| 514 | fprintf(stderr,"pack_spatial: Warning: Precision for a parameter may be too high in gribmap.txt\n"); |
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| 515 | } |
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| 516 | return (0); |
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| 517 | /* |
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| 518 | * END OF FUNCTION |
|---|
| 519 | * |
|---|
| 520 | */ |
|---|
| 521 | } |
|---|
| 522 | |
|---|
| 523 | /* |
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| 524 | * |
|---|
| 525 | ************************************************************** |
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| 526 | * B. FUNCTION grib_local_ibm |
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| 527 | * convert local_float from local floating point to |
|---|
| 528 | * IBM floating point stored in a 4-byte integer. |
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| 529 | * |
|---|
| 530 | * INTERFACE: |
|---|
| 531 | * unsigned long grib_local_ibm (local_float) |
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| 532 | * |
|---|
| 533 | * ARGUMENTS (I=input, O=output, I&O=input and output): |
|---|
| 534 | * (I) double local_float float value in local format |
|---|
| 535 | * |
|---|
| 536 | * RETURNS: |
|---|
| 537 | * the actual IBM floating point value |
|---|
| 538 | ************************************************************** |
|---|
| 539 | * |
|---|
| 540 | */ |
|---|
| 541 | #if PROTOTYPE_NEEDED |
|---|
| 542 | unsigned long grib_local_ibm (double local_float) |
|---|
| 543 | #else |
|---|
| 544 | unsigned long grib_local_ibm (local_float) |
|---|
| 545 | double local_float; |
|---|
| 546 | #endif |
|---|
| 547 | { |
|---|
| 548 | long a, b; |
|---|
| 549 | unsigned long ibm_float; |
|---|
| 550 | /* |
|---|
| 551 | * |
|---|
| 552 | * B.1.a IF (local float value is zero) THEN |
|---|
| 553 | * SET the ibm float to zero too |
|---|
| 554 | */ |
|---|
| 555 | if (local_float == 0.) { |
|---|
| 556 | ibm_float = 0; |
|---|
| 557 | } else { |
|---|
| 558 | /* |
|---|
| 559 | * B.1.b ELSE |
|---|
| 560 | * CONVERT to IBM floating point |
|---|
| 561 | * ! IBM floating point is stored in 4 bytes as: |
|---|
| 562 | * ! saaaaaaa bbbbbbbb bbbbbbbb bbbbbbbb |
|---|
| 563 | * ! where s is sign bit, 0 -> positive, 1 -> negative |
|---|
| 564 | * ! a is 7-bit characteristic |
|---|
| 565 | * ! b is 24-bit fraction |
|---|
| 566 | * ! s, a and b are obtained from local_float (local 32-bit float) as |
|---|
| 567 | * ! s = sign(local_float) |
|---|
| 568 | * ! a = ceil(log10(local_float) / log10(16.)) + 64 |
|---|
| 569 | * ! b = local_float / 16**(a-64) * 2**24 |
|---|
| 570 | * B.1.b ENDIF |
|---|
| 571 | */ |
|---|
| 572 | a = ceil(log10(fabs(local_float)) / log10(16.)) + 64; |
|---|
| 573 | /* Added by Todd Hutchinson, 8/13/99 */ |
|---|
| 574 | /* This fixes a problem when local_float == 256, etc. */ |
|---|
| 575 | if ( fmod((log10(fabs(local_float))/log10(16.)),1.) == 0) { |
|---|
| 576 | a++; |
|---|
| 577 | } |
|---|
| 578 | /* Local_float == +/-1. is a special case because of log function */ |
|---|
| 579 | if ( (local_float == 1.) || (local_float == -1.)) a = 65; |
|---|
| 580 | b = (long) (fabs(local_float) * pow(16.,(double) (70 - a)) +.5) |
|---|
| 581 | & 0x00ffffff; |
|---|
| 582 | ibm_float = (((local_float > 0.) ? 0 : 1) << 31) | (a << 24) | b; |
|---|
| 583 | } |
|---|
| 584 | /* |
|---|
| 585 | * |
|---|
| 586 | * B.2 RETURN the ibm float value |
|---|
| 587 | */ |
|---|
| 588 | return ibm_float; |
|---|
| 589 | /* |
|---|
| 590 | * |
|---|
| 591 | * END OF FUNCTION |
|---|
| 592 | * |
|---|
| 593 | */ } |
|---|
| 594 | |
|---|
| 595 | /* |
|---|
| 596 | * |
|---|
| 597 | ************************************************************** |
|---|
| 598 | * C. FUNCTION: grib_ibm_local |
|---|
| 599 | * convert local_float from IBM floating point to |
|---|
| 600 | * local floating point. |
|---|
| 601 | * |
|---|
| 602 | * INTERFACE: |
|---|
| 603 | * float grib_ibm_local(ibm_float) |
|---|
| 604 | * |
|---|
| 605 | * ARGUMENTS (I=input, O=output, I&O=input and output): |
|---|
| 606 | * (I) double local_float float value in local format |
|---|
| 607 | * |
|---|
| 608 | * RETURNS: |
|---|
| 609 | * the actual local floating point |
|---|
| 610 | ************************************************************** |
|---|
| 611 | */ |
|---|
| 612 | #if PROTOTYPE_NEEDED |
|---|
| 613 | float grib_ibm_local( unsigned long ibm_float) |
|---|
| 614 | #else |
|---|
| 615 | float grib_ibm_local( ibm_float) |
|---|
| 616 | unsigned long ibm_float; |
|---|
| 617 | #endif |
|---|
| 618 | { |
|---|
| 619 | /* |
|---|
| 620 | Convert ibm_float from IBM floating point stored in a 4-byte integer |
|---|
| 621 | to local floating point. |
|---|
| 622 | * |
|---|
| 623 | * C.1 DETERMINE local floating point |
|---|
| 624 | * ! IBM floating point is stored in 4 bytes as: |
|---|
| 625 | * ! saaaaaaa bbbbbbbb bbbbbbbb bbbbbbbb |
|---|
| 626 | * ! where s is sign bit, 0 -> positive, 1 -> negative |
|---|
| 627 | * ! a is 7-bit characteristic |
|---|
| 628 | * ! b is 24-bit fraction |
|---|
| 629 | * ! local_float (local 32-bit float) is recovered from |
|---|
| 630 | * ! s, a and b as |
|---|
| 631 | * ! local_float = (-1)**s * 2**(-24) * b * 16**(a-64) |
|---|
| 632 | */ |
|---|
| 633 | |
|---|
| 634 | long a, b; |
|---|
| 635 | float local_float; |
|---|
| 636 | |
|---|
| 637 | a = (ibm_float >> 24) & 0x0000007f; |
|---|
| 638 | b = ibm_float & 0x00ffffff; |
|---|
| 639 | local_float = (float) b * pow(16., (double) (a - 70)); |
|---|
| 640 | if (ibm_float >> 31) local_float = -local_float; |
|---|
| 641 | /* |
|---|
| 642 | * |
|---|
| 643 | * C.2 RETURN floating point |
|---|
| 644 | */ |
|---|
| 645 | return local_float; |
|---|
| 646 | /* |
|---|
| 647 | * END OF FUNCTION |
|---|
| 648 | * |
|---|
| 649 | */ |
|---|
| 650 | } |
|---|
