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/*
* Copyright (C) 2020-2021 Tomasz Kramkowski <tk@the-tk.com>
* SPDX-License-Identifier: MIT
*/
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <math.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
#include "common.h"
#include "pack.h"
#include "trace.h"
#define GEN_CONV_IEEE754B(type, total, nexp, nfrac) \
static type convert_ieee754b##total(uintmax_t b) \
{ \
bool isneg; \
int exp; \
type n; \
\
isneg = (b >> (total - 1)) & 0x1; \
exp = (b >> nfrac) & BITMASK(nexp); \
n = b & BITMASK(nfrac); \
\
if (exp == BITMASK(nexp)) { \
if (n) { \
return NAN; \
} else { \
return isneg ? -INFINITY : INFINITY; \
} \
} else if (exp == 0) { \
if (n == 0) \
return isneg ? -0.0 : 0.0; \
exp = -(int)(BITMASK(nexp) / 2 - 1); \
} else { \
n += 0x1p##nfrac##f; \
exp -= BITMASK(nexp) / 2; \
} \
\
n = ldexpf(n, exp - nfrac); \
\
return isneg ? -n : n; \
}
GEN_CONV_IEEE754B(float, 32, 8, 23)
GEN_CONV_IEEE754B(double, 64, 11, 52)
static uintmax_t read_val(const unsigned char *buf, size_t size, enum endian e)
{
uintmax_t val = 0;
for (size_t i = 0; i < size; i++) {
val |= (uintmax_t)(buf[i] & 0xff) << (e == LITTLE ? i : size - i - 1) * 8;
}
return val;
}
static intmax_t minval(size_t s)
{
switch (s) {
case 1: return INTMAX_C(-128);
case 2: return INTMAX_C(-32768);
case 4: return INTMAX_C(-2147483648);
default: return -INTMAX_C(9223372036854775807) - 1;
}
}
enum pack_status unpack(const void *buf_, size_t size, const char *fmt, ...)
{
enum endian endianness = BIG;
const unsigned char *buf = buf_;
size_t offset = 0;
va_list ap;
tr_call("unpack(%p, %zu, %s, ...)", buf, size, fmt);
va_start(ap, fmt);
for (int i = 0; fmt[i] != '\0'; i++) {
bool sign;
size_t count = 1, s;
union {
signed char *b;
unsigned char *B;
short *h;
unsigned short *H;
int *i;
unsigned int *I;
long *l;
unsigned long *L;
long long *q;
unsigned long long *Q;
float *f;
double *d;
} arg;
union { uintmax_t u; intmax_t s; float f; double d; } val;
tr_debug("i: %d, fmt[i]: %c", i, fmt[i]);
if (isdigit(fmt[i])) {
unsigned long long c;
char *end;
errno = 0;
c = strtoull(&fmt[i], &end, 10);
if ((c == ULLONG_MAX && errno == ERANGE) || c > SIZE_MAX)
return PACK_FMTINVAL;
count = c;
i += end - &fmt[i];
} else if (fmt[i] == '*') {
count = va_arg(ap, size_t);
i++;
}
sign = islower(fmt[i]);
tr_debug("count: %zu, i: %d, fmt[i]: %c, sign: %ssigned",
count, i, fmt[i], sign ? "" : "un");
switch (fmt[i]) {
case '>': endianness = BIG; continue;
case '<': endianness = LITTLE; continue;
case 'b': arg.b = va_arg(ap, signed char *); break;
case 'B': arg.B = va_arg(ap, unsigned char *); break;
case 'h': arg.h = va_arg(ap, short *); break;
case 'H': arg.H = va_arg(ap, unsigned short *); break;
case 'i': arg.i = va_arg(ap, int *); break;
case 'I': arg.I = va_arg(ap, unsigned *); break;
case 'l': arg.l = va_arg(ap, long *); break;
case 'L': arg.L = va_arg(ap, unsigned long *); break;
case 'q': arg.q = va_arg(ap, long long *); break;
case 'Q': arg.Q = va_arg(ap, unsigned long long *); break;
case 'f': arg.f = va_arg(ap, float *); break;
case 'd': arg.d = va_arg(ap, double *); break;
case 'x': break;
default: return PACK_FMTINVAL;
}
s = getsize(fmt[i]);
tr_debug("s: %zu", s);
if (s == (size_t)-1) return PACK_FMTINVAL;
if (size - offset < s * count) return PACK_TOOSMALL;
if (fmt[i] == 'x') goto skip;
for (size_t j = 0; j < count; j++) {
val.u = read_val(buf + offset + s * j, s, endianness);
tr_debug("val.u: %" PRIuMAX ", at: %zu", val.u, offset + s * j);
if (fmt[i] == 'f') {
float f = convert_ieee754b32(val.u);
val.f = f;
tr_debug("val.f: %f", val.f);
} else if (fmt[i] == 'd') {
double d = convert_ieee754b64(val.u);
val.d = d;
tr_debug("val.d: %f", val.d);
} else if (sign) {
intmax_t vals;
if (!(val.u & (UINTMAX_C(1) << (s * 8 - 1)))) {
vals = val.u;
} else {
vals = minval(s);
vals += val.u ^ (UINTMAX_C(1) << (s * 8 - 1));
}
val.s = vals;
tr_debug("val.s: %" PRIdMAX, val.s);
}
switch (fmt[i]) {
case 'b': arg.b[j] = val.s; break;
case 'B': arg.B[j] = val.u; break;
case 'h': arg.h[j] = val.s; break;
case 'H': arg.H[j] = val.u; break;
case 'i': arg.i[j] = val.s; break;
case 'I': arg.I[j] = val.u; break;
case 'l': arg.l[j] = val.s; break;
case 'L': arg.L[j] = val.u; break;
case 'q': arg.q[j] = val.s; break;
case 'Q': arg.Q[j] = val.u; break;
case 'f': arg.f[j] = val.f; break;
case 'd': arg.d[j] = val.d; break;
}
}
skip:
offset += s * count;
}
va_end(ap);
return PACK_OK;
}
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