mirror of https://gerrit.osmocom.org/asn1c
387 lines
8.5 KiB
C
387 lines
8.5 KiB
C
/*-
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* Copyright (c) 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
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* Redistribution and modifications are permitted subject to BSD license.
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*/
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#include <REAL.h>
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#include <INTEGER.h>
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#include <stdlib.h> /* for strtod(3) */
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#include <math.h>
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#include <errno.h>
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#include <assert.h>
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#undef INT_MAX
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#define INT_MAX ((int)(((unsigned int)-1) >> 1))
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#ifndef INFINITY
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#define INFINITY HUGE_VAL
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#endif
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#ifndef NAN
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static const double nan0;
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#define NAN (nan0/nan0)
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#endif
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/*
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* REAL basic type description.
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*/
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static ber_tlv_tag_t asn1_DEF_REAL_tags[] = {
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(ASN_TAG_CLASS_UNIVERSAL | (9 << 2))
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};
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asn1_TYPE_descriptor_t asn1_DEF_REAL = {
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"REAL",
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asn_generic_no_constraint,
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INTEGER_decode_ber, /* Implemented in terms of INTEGER type */
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INTEGER_encode_der,
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REAL_print,
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INTEGER_free,
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0, /* Use generic outmost tag fetcher */
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asn1_DEF_REAL_tags,
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sizeof(asn1_DEF_REAL_tags) / sizeof(asn1_DEF_REAL_tags[0]),
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asn1_DEF_REAL_tags, /* Same as above */
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sizeof(asn1_DEF_REAL_tags) / sizeof(asn1_DEF_REAL_tags[0]),
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0, /* Always in primitive form */
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0, 0, /* No members */
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0 /* No specifics */
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};
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int
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REAL_print(asn1_TYPE_descriptor_t *td, const void *sptr, int ilevel,
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asn_app_consume_bytes_f *cb, void *app_key) {
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const REAL_t *st = (const REAL_t *)sptr;
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char buf[128];
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double d;
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int ret;
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(void)td; /* Unused argument */
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(void)ilevel; /* Unused argument */
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if(!st)
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return cb("<absent>", 8, app_key);
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if(asn1_REAL2double(st, &d))
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return cb("<error>", 7, app_key);
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ret = snprintf(buf, sizeof(buf), "%f", d);
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if(ret < 0 || ret >= sizeof(buf))
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return cb("<error>", 7, app_key);
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return cb(buf, ret, app_key);
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}
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int
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asn1_REAL2double(const REAL_t *st, double *dbl_value) {
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unsigned long octv;
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if(!st || !st->buf) {
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errno = EINVAL;
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return -1;
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}
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if(st->size == 0) {
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*dbl_value = 0;
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return 0;
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}
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octv = st->buf[0]; /* unsigned byte */
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switch(octv & 0xC0) {
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case 0x40: /* X.690: 8.5.8 */
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/* "SpecialRealValue" */
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/* Be liberal in what you accept...
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if(st->size != 1) ...
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*/
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switch(st->buf[0]) {
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case 0x40: /* 01000000: PLUS-INFINITY */
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*dbl_value = INFINITY;
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return 0;
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case 0x41: /* 01000001: MINUS-INFINITY */
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*dbl_value = -INFINITY;
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return 0;
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/*
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* The following cases are defined by
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* X.690 Amendment 1 (10/03)
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*/
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case 0x42: /* 01000010: NOT-A-NUMBER */
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*dbl_value = NAN;
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return 0;
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case 0x43: /* 01000011: minus zero */
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*dbl_value = NAN;
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return 0;
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}
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errno = EINVAL;
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return -1;
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case 0x00: { /* X.690: 8.5.6 */
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/*
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* Decimal. NR{1,2,3} format.
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*/
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double d;
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assert(st->buf[st->size - 1] == 0); /* Security, vashu mat' */
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d = strtod((char *)st->buf, 0);
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if(finite(d)) {
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*dbl_value = d;
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return 0;
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} else {
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errno = ERANGE;
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return 0;
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}
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}
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}
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/*
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* Binary representation.
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*/
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{
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double m;
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int expval; /* exponent value */
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unsigned int elen; /* exponent value length, in octets */
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unsigned int scaleF;
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unsigned int baseF;
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uint8_t *ptr;
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uint8_t *end;
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int sign;
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switch((octv & 0x30) >> 4) {
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case 0x00: baseF = 1; break; /* base 2 */
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case 0x01: baseF = 3; break; /* base 8 */
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case 0x02: baseF = 4; break; /* base 16 */
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default:
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/* Reserved field, can't parse now. */
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errno = EINVAL;
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return -1;
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}
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sign = (octv & 0x40); /* bit 7 */
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scaleF = (octv & 0x0C) >> 2; /* bits 4 to 3 */
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if(st->size <= (1 + (octv & 0x03))) {
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errno = EINVAL;
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return -1;
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}
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if((octv & 0x03) == 0x11) {
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/* 8.5.6.4, case d) */
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elen = st->buf[1]; /* unsigned binary number */
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if(elen == 0 || st->size <= (2 + elen)) {
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errno = EINVAL;
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return -1;
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}
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ptr = &st->buf[2];
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} else {
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elen = (octv & 0x03);
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ptr = &st->buf[1];
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}
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/* Fetch the multibyte exponent */
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expval = (int)(*(int8_t *)ptr);
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end = ptr + elen + 1;
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for(ptr++; ptr < end; ptr++)
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expval = (expval * 256) + *ptr;
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m = 0.0; /* Initial mantissa value */
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/* Okay, the exponent is here. Now, what about mantissa? */
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end = st->buf + st->size;
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if(ptr < end) {
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for(; ptr < end; ptr++)
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m = scalbn(m, 8) + *ptr;
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}
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ASN_DEBUG("m=%.10f, scF=%d, bF=%d, expval=%d, ldexp()=%f, scalbn()=%f",
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m, scaleF, baseF, expval,
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ldexp(m, expval * baseF + scaleF),
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scalbn(m, scaleF) * pow(pow(2, baseF), expval)
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);
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/*
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* (S * N * 2^F) * B^E
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* Essentially:
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m = scalbn(m, scaleF) * pow(pow(2, base), expval);
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*/
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m = ldexp(m, expval * baseF + scaleF);
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if(finite(m)) {
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*dbl_value = sign ? -m : m;
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} else {
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errno = ERANGE;
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return -1;
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}
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} /* if(binary_format) */
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return 0;
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}
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/*
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* Assume IEEE 754 floating point: standard 64 bit double.
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* [1 bit sign] [11 bits exponent] [52 bits mantissa]
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*/
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int
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asn1_double2REAL(REAL_t *st, double dbl_value) {
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#ifdef WORDS_BIGENDIAN /* Known to be big-endian */
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int littleEndian = 0;
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#else /* need to test: have no explicit information */
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unsigned int LE = 1;
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int littleEndian = *(unsigned char *)&LE;
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#endif
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uint8_t buf[16]; /* More than enough for 8-byte dbl_value */
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uint8_t dscr[sizeof(dbl_value)]; /* double value scratch pad */
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/* Assertion guards: won't even compile, if unexpected double size */
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char assertion_buffer1[9 - sizeof(dbl_value)] __attribute__((unused));
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char assertion_buffer2[sizeof(dbl_value) - 7] __attribute__((unused));
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uint8_t *ptr = buf;
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uint8_t *mstop; /* Last byte of mantissa */
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unsigned int mval; /* Value of the last byte of mantissa */
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unsigned int bmsign; /* binary mask with sign */
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unsigned int buflen;
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unsigned int accum;
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int expval;
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if(!st) {
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errno = EINVAL;
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return -1;
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}
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expval = ilogb(dbl_value);
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if(expval == -INT_MAX /* Also catches (dbl_value == 0) */
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|| expval == INT_MAX /* catches finite() which catches isnan() */
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) {
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if(!st->buf || st->size < 2) {
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(void *)ptr = MALLOC(2);
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if(!ptr) return -1;
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st->buf = ptr;
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}
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/* fpclassify(3) is not portable yet */
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if(expval == -INT_MAX) {
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if(signbit(dbl_value)) {
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st->buf[0] = 0x80 | 0x40;
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st->buf[1] = 0;
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st->size = 2;
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} else {
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st->buf[0] = 0; /* JIC */
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st->size = 0;
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}
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} else if(isinf(dbl_value)) {
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if(signbit(dbl_value)) {
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st->buf[0] = 0x41; /* MINUS-INFINITY */
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} else {
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st->buf[0] = 0x40; /* PLUS-INFINITY */
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}
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st->buf[1] = 0;
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st->size = 1;
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} else {
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st->buf[0] = 0x42; /* NaN */
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st->buf[1] = 0;
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st->size = 1;
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}
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return 0;
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}
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if(littleEndian) {
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uint8_t *s = ((uint8_t *)&dbl_value) + sizeof(dbl_value) - 2;
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uint8_t *d;
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bmsign = 0x80 | ((s[1] >> 1) & 0x40); /* binary mask & - */
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for(mstop = d = dscr; s >= (uint8_t *)&dbl_value; d++, s--) {
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*d = *s;
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if(*d) mstop = d;
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}
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} else {
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uint8_t *s = ((uint8_t *)&dbl_value) + 1;
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uint8_t *end = ((uint8_t *)&dbl_value) + sizeof(double);
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uint8_t *d;
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bmsign = 0x80 | ((s[-1] >> 1) & 0x40); /* binary mask & - */
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for(mstop = d = dscr; s < end; d++, s++) {
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*d = *s;
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if(*d) mstop = d;
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}
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}
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/* Remove parts of the exponent, leave mantissa and explicit 1. */
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dscr[0] = 0x10 | (dscr[0] & 0x0f);
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/* Adjust exponent in a very unobvious way */
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expval -= 8 * ((mstop - dscr) + 1) - 4;
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/* This loop ensures DER conformance by forcing mantissa odd: 11.3.1 */
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mval = *mstop;
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if(mval && !(mval & 1)) {
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unsigned int shift_count = 1;
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unsigned int ishift;
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uint8_t *mptr;
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/*
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* Figure out what needs to be done to make mantissa odd.
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*/
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if(!(mval & 0x0f)) /* Speed-up a little */
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shift_count = 4;
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while(((mval >> shift_count) & 1) == 0)
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shift_count++;
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ishift = 8 - shift_count;
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accum = 0;
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/* Go over the buffer, shifting it shift_count bits right. */
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for(mptr = dscr; mptr <= mstop; mptr++) {
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mval = *mptr;
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*mptr = accum | (mval >> shift_count);
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accum = mval << ishift;
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}
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/* Adjust mantissa appropriately. */
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expval += shift_count;
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}
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if(expval < 0) {
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if((expval >> 7) == -1) {
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*ptr++ = bmsign | 0x00;
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*ptr++ = expval;
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} else if((expval >> 15) == -1) {
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*ptr++ = bmsign | 0x01;
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*ptr++ = expval >> 8;
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*ptr++ = expval;
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} else {
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assert((expval >> 23) == -1);
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*ptr++ = bmsign | 0x02;
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*ptr++ = expval >> 16;
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*ptr++ = expval >> 8;
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*ptr++ = expval;
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}
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} else if(expval <= 0x7f) {
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*ptr++ = bmsign | 0x00;
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*ptr++ = expval;
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} else if(expval <= 0x7fff) {
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*ptr++ = bmsign | 0x01;
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*ptr++ = expval >> 8;
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*ptr++ = expval;
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} else {
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assert(expval <= 0x7fffff);
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*ptr++ = bmsign | 0x02;
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*ptr++ = expval >> 16;
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*ptr++ = expval >> 8;
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*ptr++ = expval;
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}
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buflen = (mstop - dscr) + 1;
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memcpy(ptr, dscr, buflen);
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ptr += buflen;
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buflen = ptr - buf;
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(void *)ptr = MALLOC(buflen + 1);
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if(!ptr) return -1;
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memcpy(ptr, buf, buflen);
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buf[buflen] = 0; /* JIC */
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if(st->buf) FREEMEM(st->buf);
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st->buf = ptr;
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st->size = buflen;
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return 0;
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}
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