106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
#include <ctype.h>
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#include <stdlib.h>
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#include <math.h>
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#include "sics.h"
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/*
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* conversions:
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* hex2float
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* float2hex
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*
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* Markus Zolliker Aug 2010
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*/
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/*-------------------------------------------------------------------------*/
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void double2ieee(double input, char ieee[4])
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{
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/* convert double to IEEE 32 bit floating number (denormalized numbers are considered as zero) */
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long mantissa;
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int exponent;
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if (input == 0) {
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ieee[0] = 0;
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ieee[1] = 0;
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ieee[2] = 0;
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ieee[3] = 0;
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} else {
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mantissa = 0x1000000 * (frexp(fabs(input), &exponent));
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exponent = exponent - 1 + 127;
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if (exponent < 0) {
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exponent = 0;
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} else if (exponent > 0xFE) {
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exponent = 0xFE;
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}
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if (input < 0) {
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ieee[0] = 0x80 | (exponent >> 1);
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} else {
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ieee[0] = exponent >> 1;
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}
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ieee[1] = (exponent & 1) << 7 | ((mantissa & 0x7F0000) >> 16);
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ieee[2] = (mantissa & 0xFF00) >> 8;
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ieee[3] = mantissa & 0xFF;
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}
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return;
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}
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/*-------------------------------------------------------------------------*/
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double ieee2double(char ieee[4])
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{
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/* IEEE 32 bit floating number to double (denormalized numbers are considered as zero) */
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long mantissa;
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double output;
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int exponent;
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mantissa = ((ieee[1] << 16) & 0x7FFFFF)
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| ((ieee[2] << 8) & 0xFF00)
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| ((ieee[3]) & 0xFF);
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exponent = (ieee[0] & 0x7F) * 2 + ((ieee[1] >> 7) & 1); /* raw exponent */
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if (exponent == 0 && mantissa == 0) {
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return 0.0;
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}
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output = ldexp(mantissa, -23) + 1.0;
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if (ieee[0] & 0x80) {
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output = -output;
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}
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return output * ldexp(1, exponent - 127);
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}
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/*-------------------------------------------------------------------------*/
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int CnvrtAction(SConnection *con, SicsInterp *sics, void *data,
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int argc, char *argv[]) {
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double f;
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char ieee[4];
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char result[32];
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if (argc != 3) goto Usage;
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if (strcasecmp(argv[1], "float2xieee") == 0) {
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double2ieee(atof(argv[2]), ieee);
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SCPrintf(con, eValue, "%2.2x%2.2x%2.2x%2.2x",
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ieee[0] & 0xFF, ieee[1] & 0xFF, ieee[2] & 0xFF, ieee[3] & 0xFF);
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return 1;
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} else if (strcasecmp(argv[1], "xieee2float") == 0) {
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ieee[0]=0;
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ieee[1]=0;
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ieee[2]=0;
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ieee[3]=0;
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sscanf(argv[2], "%2hhx%2hhx%2hhx%2hhx",
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ieee, ieee+1, ieee+2, ieee+3);
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snprintf(result, sizeof result, "%.7g", ieee2double(ieee));
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if (strchr(result, '.') == NULL && strchr(result, 'e') == NULL) {
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SCPrintf(con, eValue, "%s.", result);
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} else {
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SCWrite(con, result, eValue);
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}
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return 1;
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}
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Usage:
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SCPrintf(con, eError, "ERROR: Usage: cnvrt float2xieee <float>");
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SCPrintf(con, eError, " cnvrt xieee2float <hexadecimal ieee>");
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return 0;
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}
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