Line data    Source code

       1              : /*-----------------------------------------------------------------------
       2              :  * ascii.h
       3              :  *
       4              :  *   Portions Copyright (c) 1999-2026, PostgreSQL Global Development Group
       5              :  *
       6              :  * src/include/utils/ascii.h
       7              :  *
       8              :  *-----------------------------------------------------------------------
       9              :  */
      10              : 
      11              : #ifndef _ASCII_H_
      12              : #define _ASCII_H_
      13              : 
      14              : #include "port/simd.h"
      15              : 
      16              : extern 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 the
      22              :  * high-bit set. Input len must be a multiple of the chunk size (8 or 16).
      23              :  */
      24              : static inline bool
      25      1825682 : is_valid_ascii(const unsigned char *s, int len)
      26              : {
      27      1825682 :     const unsigned char *const s_end = s + len;
      28              :     Vector8     chunk;
      29      1825682 :     Vector8     highbit_cum = vector8_broadcast(0);
      30              : #ifdef USE_NO_SIMD
      31              :     Vector8     zero_cum = vector8_broadcast(0x80);
      32              : #endif
      33              : 
      34              :     Assert(len % sizeof(chunk) == 0);
      35              : 
      36      5477046 :     while (s < s_end)
      37              :     {
      38      3651364 :         vector8_load(&chunk, s);
      39              : 
      40              :         /* Capture any zero bytes in this chunk. */
      41              : #ifdef USE_NO_SIMD
      42              : 
      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, the
      46              :          * 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 max
      49              :          * 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. If
      51              :          * any input bytes did have the high bit set, it doesn't matter
      52              :          * because we check for those separately.
      53              :          */
      54              :         zero_cum &= (chunk + vector8_broadcast(0x7F));
      55              : #else
      56              : 
      57              :         /*
      58              :          * Set all bits in each lane of the highbit accumulator where input
      59              :          * bytes are zero.
      60              :          */
      61      3651364 :         highbit_cum = vector8_or(highbit_cum,
      62              :                                  vector8_eq(chunk, vector8_broadcast(0)));
      63              : #endif
      64              : 
      65              :         /* Capture all set bits in this chunk. */
      66      3651364 :         highbit_cum = vector8_or(highbit_cum, chunk);
      67              : 
      68      3651364 :         s += sizeof(chunk);
      69              :     }
      70              : 
      71              :     /* Check if any high bits in the high bit accumulator got set. */
      72      1825682 :     if (vector8_is_highbit_set(highbit_cum))
      73          588 :         return false;
      74              : 
      75              : #ifdef USE_NO_SIMD
      76              :     /* Check if any high bits in the zero accumulator got cleared. */
      77              :     if (zero_cum != vector8_broadcast(0x80))
      78              :         return false;
      79              : #endif
      80              : 
      81      1825094 :     return true;
      82              : }
      83              : 
      84              : #endif                          /* _ASCII_H_ */