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Add uleb encoding/decoding functions

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Implement Unsigned Little Endian Base 128.

Signed-off-by: Orit Wasserman <owasserm@redhat.com>

Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Orit Wasserman 2012-08-06 21:42:51 +03:00 committed by Juan Quintela
parent 9fb26641ab
commit e6546bb938
2 changed files with 41 additions and 0 deletions
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33
cutils.c
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@ -391,3 +391,36 @@ int64_t pow2floor(int64_t value)
}
return value;
}
/*
* Implementation of ULEB128 (http://en.wikipedia.org/wiki/LEB128)
* Input is limited to 14-bit numbers
*/
int uleb128_encode_small(uint8_t *out, uint32_t n)
{
g_assert(n <= 0x3fff);
if (n < 0x80) {
*out++ = n;
return 1;
} else {
*out++ = (n & 0x7f) | 0x80;
*out++ = n >> 7;
return 2;
}
}
int uleb128_decode_small(const uint8_t *in, uint32_t *n)
{
if (!(*in & 0x80)) {
*n = *in++;
return 1;
} else {
*n = *in++ & 0x7f;
/* we exceed 14 bit number */
if (*in & 0x80) {
return -1;
}
*n |= *in++ << 7;
return 2;
}
}

8
qemu-common.h
View File

@ -443,4 +443,12 @@ int64_t pow2floor(int64_t value);
#include "module.h"
/*
* Implementation of ULEB128 (http://en.wikipedia.org/wiki/LEB128)
* Input is limited to 14-bit numbers
*/
int uleb128_encode_small(uint8_t *out, uint32_t n);
int uleb128_decode_small(const uint8_t *in, uint32_t *n);
#endif