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optimize base64 decoding a bit 

it's a hot path for decoding checksums in fdb
cute-signatures
Timo Teräs 2015-06-12 09:08:31 +03:00
parent ed94d8ffba
commit 36d730e95d
1 changed files with 16 additions and 20 deletions
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36
src/blob.c
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@ -583,7 +583,7 @@ static unsigned char b64decode[] = {
};
static inline __attribute__((always_inline))
int pull_b64_chunk(unsigned char *to, const unsigned char *from, int len)
int pull_b64_chunk(unsigned char *restrict to, const unsigned char *restrict from, int len)
{
unsigned char tmp[4];
int i, r = 0;
@ -610,21 +610,20 @@ int pull_b64_chunk(unsigned char *to, const unsigned char *from, int len)
void apk_blob_pull_base64(apk_blob_t *b, apk_blob_t to)
{
unsigned char tmp[4];
unsigned char *src = (unsigned char *) b->ptr;
unsigned char *dst = (unsigned char *) to.ptr;
int i, r, needed;
unsigned char *restrict src = (unsigned char *) b->ptr;
unsigned char *restrict dst = (unsigned char *) to.ptr;
unsigned char *dend;
int r, needed;
if (unlikely(APK_BLOB_IS_NULL(*b)))
return;
needed = ((to.len + 2) / 3) * 4;
if (unlikely(b->len < needed)) {
*b = APK_BLOB_NULL;
return;
}
if (unlikely(b->len < needed)) goto err;
r = 0;
for (i = 0; i < to.len / 3; i++, src += 4, dst += 3) {
dend = dst + to.len - 2;
for (; dst < dend; src += 4, dst += 3) {
r |= tmp[0] = b64decode[src[0]];
r |= tmp[1] = b64decode[src[1]];
r |= tmp[2] = b64decode[src[2]];
@ -633,21 +632,18 @@ void apk_blob_pull_base64(apk_blob_t *b, apk_blob_t to)
dst[1] = (tmp[1] << 4 | tmp[2] >> 2);
dst[2] = (((tmp[2] << 6) & 0xc0) | tmp[3]);
}
if (unlikely(r == 0xff)) {
*b = APK_BLOB_NULL;
return;
}
if (unlikely(r == 0xff)) goto err;
i = to.len % 3;
if (i != 0) {
if (pull_b64_chunk(dst, src, i) != 0) {
*b = APK_BLOB_NULL;
return;
}
}
dend += 2;
if (dst != dend &&
pull_b64_chunk(dst, src, dend - dst) != 0)
goto err;
b->ptr += needed;
b->len -= needed;
return;
err:
*b = APK_BLOB_NULL;
}
static apk_blob_t atom_hash_get_key(apk_hash_item item)