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json_tokener: optimize check for hex characters

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speedup for 32-bit: ~1%
speedup for 64-bit: ~1%
This commit is contained in:
Ramiro Polla
2018-12-08 19:13:25 +01:00
parent 158c248d5c
commit 45c601bfa4
1 changed files with 9 additions and 2 deletions
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11
json_tokener.c
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@@ -66,6 +66,13 @@ static int is_ws_char(char c)
|| c == '\r'; || c == '\r';
} }
static int is_hex_char(char c)
{
return (c >= '0' && c <= '9')
|| (c >= 'A' && c <= 'F')
|| (c >= 'a' && c <= 'f');
}
/* Use C99 NAN by default; if not available, nan("") should work too. */ /* Use C99 NAN by default; if not available, nan("") should work too. */
#ifndef NAN #ifndef NAN
#define NAN nan("") #define NAN nan("")
@@ -609,7 +616,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
/* Handle a 4-byte sequence, or two sequences if a surrogate pair */ /* Handle a 4-byte sequence, or two sequences if a surrogate pair */
while(1) { while(1) {
if (c && strchr(json_hex_chars, c)) { if (c && is_hex_char(c)) {
tok->ucs_char += ((unsigned int)jt_hexdigit(c) << ((3-tok->st_pos++)*4)); tok->ucs_char += ((unsigned int)jt_hexdigit(c) << ((3-tok->st_pos++)*4));
if(tok->st_pos == 4) { if(tok->st_pos == 4) {
unsigned char unescaped_utf[4]; unsigned char unescaped_utf[4];
@@ -641,7 +648,7 @@ struct json_object* json_tokener_parse_ex(struct json_tokener *tok,
got_hi_surrogate = tok->ucs_char; got_hi_surrogate = tok->ucs_char;
/* Not at end, and the next two chars should be "\u" */ /* Not at end, and the next two chars should be "\u" */
if ((len == -1 || len > (tok->char_offset + 2)) && if ((len == -1 || len > (tok->char_offset + 2)) &&
// str[0] != '0' && // implied by json_hex_chars, above. // str[0] != '0' && // implied by is_hex_char, above.
(str[1] == '\\') && (str[1] == '\\') &&
(str[2] == 'u')) (str[2] == 'u'))
{ {