radare2/libr/util/uleb128.c
2015-05-04 10:03:58 +02:00

101 lines
2.0 KiB
C

/* radare - LGPL - Copyright 2014-2015 - pancake */
#include <r_util.h>
/* dex/dwarf uleb128 implementation */
R_API const ut8 *r_uleb128 (const ut8 *data, int datalen, ut64 *v) {
ut8 c;
ut64 s, sum = 0;
const ut8 *data_end;
if (v) *v = 0LL;
if (datalen==ST32_MAX) {
// WARNING; possible overflow
datalen = 0xffff;
} else
if (datalen<0) {
return NULL;
}
data_end = data + datalen;
if (data && datalen>0) {
if (*data) {
for (s = 0; data<data_end; s += 7) {
c = *(data++) & 0xff;
sum |= ((ut32) (c&0x7f) << s);
if (!(c&0x80)) break;
}
} else data++;
}
if (v) *v = sum;
return data;
}
/* data is the char array containing the uleb number
* datalen will point (if not NULL) to the length of the uleb number
* v (if not NULL) will point to the data's value (if fitting the size of an ut64)
*/
R_API const ut8 *r_uleb128_decode (const ut8 *data, int *datalen, ut64 *v) {
ut8 c = 0xff;
ut64 s = 0, sum = 0, l = 0;
if (data && *data) {
do {
c = *(data++) & 0xff;
sum |= ((ut32) (c&0x7f) << s);
s += 7;
l++;
} while (c & 0x80);
}
if (v) *v = sum;
if (datalen) *datalen = l;
return data;
}
R_API const ut8 *r_uleb128_encode (const ut64 s, int *len) {
ut8 c = 0;
int l = 0;
ut8 *otarget = NULL, *target = NULL;
ut64 source = s;
do {
l++;
if ((otarget = realloc (otarget, l)) == NULL) {
l = 0;
break;
}
target = otarget+l-1;
c = 0; //May not be necessary
c = source & 0x7f;
source >>= 7;
if (source) c |= 0x80;
*(target) = c;
} while (source);
if (len) *len = l;
return otarget;
}
R_API const ut8 *r_leb128 (const ut8 *data, st64 *v) {
ut8 c = 0;
st64 s = 0, sum = 0;
if (data) {
for (s = 0; *data;) {
c = *(data++) & 0x0ff;
sum |= ((st64) (c & 0x7f) << s);
s += 7;
if (!(c & 0x80)) break;
}
}
if ((s < (8 * sizeof (sum))) && (c & 0x40)) {
sum |= -((st64)1 << s);
}
if (v) *v = sum;
return data;
}
#if 0
main() {
ut32 n;
ut8 *buf = "\x10\x02\x90\x88";
r_uleb128 (buf, &n);
printf ("n = %d\n", n);
}
#endif