mirror of
https://github.com/python/cpython.git
synced 2024-11-24 17:47:13 +01:00
134 lines
3.7 KiB
C
134 lines
3.7 KiB
C
/* Finding the optimal width of unicode characters in a buffer */
|
|
|
|
#if STRINGLIB_IS_UNICODE
|
|
|
|
/* 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 */
|
|
#endif /* STRINGLIB_IS_UNICODE */
|
|
|