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static inline int
dec_loop_generic_32_inner (const uint8_t **s, uint8_t **o, size_t *rounds)
{
const uint32_t str
= base64_table_dec_32bit_d0[(*s)[0]]
| base64_table_dec_32bit_d1[(*s)[1]]
| base64_table_dec_32bit_d2[(*s)[2]]
| base64_table_dec_32bit_d3[(*s)[3]];
#if BASE64_LITTLE_ENDIAN
// LUTs for little-endian set MSB in case of invalid character:
if (str & UINT32_C(0x80000000)) {
return 0;
}
#else
// LUTs for big-endian set LSB in case of invalid character:
if (str & UINT32_C(1)) {
return 0;
}
#endif
// Store the output:
memcpy(*o, &str, sizeof (str));
*s += 4;
*o += 3;
*rounds -= 1;
return 1;
}
static inline void
dec_loop_generic_32 (const uint8_t **s, size_t *slen, uint8_t **o, size_t *olen)
{
if (*slen < 8) {
return;
}
// Process blocks of 4 bytes per round. Because one extra zero byte is
// written after the output, ensure that there will be at least 4 bytes
// of input data left to cover the gap. (Two data bytes and up to two
// end-of-string markers.)
size_t rounds = (*slen - 4) / 4;
*slen -= rounds * 4; // 4 bytes consumed per round
*olen += rounds * 3; // 3 bytes produced per round
do {
if (rounds >= 8) {
if (dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds)) {
continue;
}
break;
}
if (rounds >= 4) {
if (dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds)) {
continue;
}
break;
}
if (rounds >= 2) {
if (dec_loop_generic_32_inner(s, o, &rounds) &&
dec_loop_generic_32_inner(s, o, &rounds)) {
continue;
}
break;
}
dec_loop_generic_32_inner(s, o, &rounds);
break;
} while (rounds > 0);
// Adjust for any rounds that were skipped:
*slen += rounds * 4;
*olen -= rounds * 3;
}
|
