codekingpro/portable-devtools

1/*-----------------------------------------------------------------------2 * ascii.h3 *4 *	 Portions Copyright (c) 1999-2023, PostgreSQL Global Development Group5 *6 * src/include/utils/ascii.h7 *8 *-----------------------------------------------------------------------9 */10 11#ifndef _ASCII_H_12#define _ASCII_H_13 14#include "port/simd.h"15 16extern void ascii_safe_strlcpy(char *dest, const char *src, size_t destsiz);17 18/*19 * Verify a chunk of bytes for valid ASCII.20 *21 * Returns false if the input contains any zero bytes or bytes with the22 * high-bit set. Input len must be a multiple of the chunk size (8 or 16).23 */24static inline bool25is_valid_ascii(const unsigned char *s, int len)26{27	const unsigned char *const s_end = s + len;28	Vector8		chunk;29	Vector8		highbit_cum = vector8_broadcast(0);30#ifdef USE_NO_SIMD31	Vector8		zero_cum = vector8_broadcast(0x80);32#endif33 34	Assert(len % sizeof(chunk) == 0);35 36	while (s < s_end)37	{38		vector8_load(&chunk, s);39 40		/* Capture any zero bytes in this chunk. */41#ifdef USE_NO_SIMD42 43		/*44		 * First, add 0x7f to each byte. This sets the high bit in each byte,45		 * unless it was a zero. If any resulting high bits are zero, the46		 * corresponding high bits in the zero accumulator will be cleared.47		 *48		 * If none of the bytes in the chunk had the high bit set, the max49		 * value each byte can have after the addition is 0x7f + 0x7f = 0xfe,50		 * and we don't need to worry about carrying over to the next byte. If51		 * any input bytes did have the high bit set, it doesn't matter52		 * because we check for those separately.53		 */54		zero_cum &= (chunk + vector8_broadcast(0x7F));55#else56 57		/*58		 * Set all bits in each lane of the highbit accumulator where input59		 * bytes are zero.60		 */61		highbit_cum = vector8_or(highbit_cum,62								 vector8_eq(chunk, vector8_broadcast(0)));63#endif64 65		/* Capture all set bits in this chunk. */66		highbit_cum = vector8_or(highbit_cum, chunk);67 68		s += sizeof(chunk);69	}70 71	/* Check if any high bits in the high bit accumulator got set. */72	if (vector8_is_highbit_set(highbit_cum))73		return false;74 75#ifdef USE_NO_SIMD76	/* Check if any high bits in the zero accumulator got cleared. */77	if (zero_cum != vector8_broadcast(0x80))78		return false;79#endif80 81	return true;82}83 84#endif							/* _ASCII_H_ */85