/* Finding the optimal width of unicode characters in a buffer */ #if !STRINGLIB_IS_UNICODE # error "find_max_char.h is specific to Unicode" #endif /* Mask to quickly check whether a C 'long' contains a non-ASCII, UTF8-encoded char. */ #if (SIZEOF_LONG == 8) # define UCS1_ASCII_CHAR_MASK 0x8080808080808080UL #elif (SIZEOF_LONG == 4) # define UCS1_ASCII_CHAR_MASK 0x80808080UL #else # error C 'long' size should be either 4 or 8! #endif #if STRINGLIB_SIZEOF_CHAR == 1 Py_LOCAL_INLINE(Py_UCS4) STRINGLIB(find_max_char)(const STRINGLIB_CHAR *begin, const STRINGLIB_CHAR *end) { const unsigned char *p = (const unsigned char *) begin; const unsigned char *aligned_end = (const unsigned char *) _Py_ALIGN_DOWN(end, SIZEOF_LONG); while (p < end) { if (_Py_IS_ALIGNED(p, SIZEOF_LONG)) { /* Help register allocation */ const unsigned char *_p = p; while (_p < aligned_end) { unsigned long value = *(unsigned long *) _p; if (value & UCS1_ASCII_CHAR_MASK) return 255; _p += SIZEOF_LONG; } p = _p; if (p == end) break; } if (*p++ & 0x80) return 255; } return 127; } #undef ASCII_CHAR_MASK #else /* STRINGLIB_SIZEOF_CHAR == 1 */ #define MASK_ASCII 0xFFFFFF80 #define MASK_UCS1 0xFFFFFF00 #define MASK_UCS2 0xFFFF0000 #define MAX_CHAR_ASCII 0x7f #define MAX_CHAR_UCS1 0xff #define MAX_CHAR_UCS2 0xffff #define MAX_CHAR_UCS4 0x10ffff Py_LOCAL_INLINE(Py_UCS4) STRINGLIB(find_max_char)(const STRINGLIB_CHAR *begin, const STRINGLIB_CHAR *end) { #if STRINGLIB_SIZEOF_CHAR == 2 const Py_UCS4 mask_limit = MASK_UCS1; const Py_UCS4 max_char_limit = MAX_CHAR_UCS2; #elif STRINGLIB_SIZEOF_CHAR == 4 const Py_UCS4 mask_limit = MASK_UCS2; const Py_UCS4 max_char_limit = MAX_CHAR_UCS4; #else #error Invalid STRINGLIB_SIZEOF_CHAR (must be 1, 2 or 4) #endif Py_UCS4 mask; Py_ssize_t n = end - begin; const STRINGLIB_CHAR *p = begin; const STRINGLIB_CHAR *unrolled_end = begin + _Py_SIZE_ROUND_DOWN(n, 4); Py_UCS4 max_char; max_char = MAX_CHAR_ASCII; mask = MASK_ASCII; while (p < unrolled_end) { STRINGLIB_CHAR bits = p[0] | p[1] | p[2] | p[3]; if (bits & mask) { if (mask == mask_limit) { /* Limit reached */ return max_char_limit; } if (mask == MASK_ASCII) { max_char = MAX_CHAR_UCS1; mask = MASK_UCS1; } else { /* mask can't be MASK_UCS2 because of mask_limit above */ assert(mask == MASK_UCS1); max_char = MAX_CHAR_UCS2; mask = MASK_UCS2; } /* We check the new mask on the same chars in the next iteration */ continue; } p += 4; } while (p < end) { if (p[0] & mask) { if (mask == mask_limit) { /* Limit reached */ return max_char_limit; } if (mask == MASK_ASCII) { max_char = MAX_CHAR_UCS1; mask = MASK_UCS1; } else { /* mask can't be MASK_UCS2 because of mask_limit above */ assert(mask == MASK_UCS1); max_char = MAX_CHAR_UCS2; mask = MASK_UCS2; } /* We check the new mask on the same chars in the next iteration */ continue; } p++; } return max_char; } #undef MASK_ASCII #undef MASK_UCS1 #undef MASK_UCS2 #undef MAX_CHAR_ASCII #undef MAX_CHAR_UCS1 #undef MAX_CHAR_UCS2 #undef MAX_CHAR_UCS4 #endif /* STRINGLIB_SIZEOF_CHAR == 1 */