| /*----------------------------------------------------------------------- | |
| * ascii.h | |
| * | |
| * Portions Copyright (c) 1999-2024, PostgreSQL Global Development Group | |
| * | |
| * src/include/utils/ascii.h | |
| * | |
| *----------------------------------------------------------------------- | |
| */ | |
| extern void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz); | |
| /* | |
| * Verify a chunk of bytes for valid ASCII. | |
| * | |
| * Returns false if the input contains any zero bytes or bytes with the | |
| * high-bit set. Input len must be a multiple of the chunk size (8 or 16). | |
| */ | |
| static inline bool | |
| is_valid_ascii(const unsigned char *s, int len) | |
| { | |
| const unsigned char *const s_end = s + len; | |
| Vector8 chunk; | |
| Vector8 highbit_cum = vector8_broadcast(0); | |
| Vector8 zero_cum = vector8_broadcast(0x80); | |
| Assert(len % sizeof(chunk) == 0); | |
| while (s < s_end) | |
| { | |
| vector8_load(&chunk, s); | |
| /* Capture any zero bytes in this chunk. */ | |
| /* | |
| * First, add 0x7f to each byte. This sets the high bit in each byte, | |
| * unless it was a zero. If any resulting high bits are zero, the | |
| * corresponding high bits in the zero accumulator will be cleared. | |
| * | |
| * If none of the bytes in the chunk had the high bit set, the max | |
| * value each byte can have after the addition is 0x7f + 0x7f = 0xfe, | |
| * and we don't need to worry about carrying over to the next byte. If | |
| * any input bytes did have the high bit set, it doesn't matter | |
| * because we check for those separately. | |
| */ | |
| zero_cum &= (chunk + vector8_broadcast(0x7F)); | |
| /* | |
| * Set all bits in each lane of the highbit accumulator where input | |
| * bytes are zero. | |
| */ | |
| highbit_cum = vector8_or(highbit_cum, | |
| vector8_eq(chunk, vector8_broadcast(0))); | |
| /* Capture all set bits in this chunk. */ | |
| highbit_cum = vector8_or(highbit_cum, chunk); | |
| s += sizeof(chunk); | |
| } | |
| /* Check if any high bits in the high bit accumulator got set. */ | |
| if (vector8_is_highbit_set(highbit_cum)) | |
| return false; | |
| /* Check if any high bits in the zero accumulator got cleared. */ | |
| if (zero_cum != vector8_broadcast(0x80)) | |
| return false; | |
| return true; | |
| } | |