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Bug 29241, nsID::Parse used scanf to parse UUID:s which was very slow. This custom parsing should shave 1.6% of mozilla startup time. r=jag sr=jband

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bratell%lysator.liu.se 2001-02-04 09:36:22 +00:00
parent c689459a0e
commit 152411bf4c
1 changed files with 67 additions and 22 deletions
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89
xpcom/base/nsID.cpp
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@ -17,7 +17,8 @@
* Copyright (C) 1998 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
* Contributor(s):
* Daniel Bratell <bratell@lysator.liu.se>
*/
#include "nsID.h"
#include "prprf.h"
@ -29,38 +30,82 @@ static const char gIDFormat[] =
static const char gIDFormat2[] =
"%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x";
/**
* Multiplies the_int_var with 16 (0x10) and adds the value of the
* hexadecimal digit the_char. If it fails it returns PR_FALSE from
* the function it's used in.
*/
#define ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(the_char, the_int_var) \
the_int_var = (the_int_var << 4) + the_char; \
if(the_char >= '0' && the_char <= '9') the_int_var -= '0'; \
else if(the_char >= 'a' && the_char <= 'f') the_int_var -= 'a'-10; \
else if(the_char >= 'A' && the_char <= 'F') the_int_var -= 'A'-10; \
else return PR_FALSE
/**
* Parses number_of_chars characters from the char_pointer pointer and
* puts the number in the dest_variable. The pointer is moved to point
* at the first character after the parsed ones. If it fails it returns
* PR_FALSE from the function the macro is used in.
*/
#define PARSE_CHARS_TO_NUM(char_pointer, dest_variable, number_of_chars) \
do { PRInt32 _i=number_of_chars; \
dest_variable = 0; \
while(_i) { \
ADD_HEX_CHAR_TO_INT_OR_RETURN_FALSE(*char_pointer, dest_variable); \
char_pointer++; \
_i--; \
} } while(0)
/**
* Parses a hyphen from the char_pointer string. If there is no hyphen there
* the function returns PR_FALSE from the function it's used in. The
* char_pointer is advanced one step.
*/
#define PARSE_HYPHEN(char_pointer) if(*(char_pointer++) != '-') return PR_FALSE
/*
* Turns a {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} string into
* an nsID
* an nsID. It can also handle the old format without the { and }.
*/
NS_COM PRBool nsID::Parse(const char *aIDStr)
{
PRInt32 count = 0;
PRInt32 n1, n2, n3[8];
PRInt32 n0;
::memset(n3, 0, sizeof(n3));
if (NULL != aIDStr) {
count = PR_sscanf(aIDStr,
(aIDStr[0] == '{') ? gIDFormat : gIDFormat2,
&n0, &n1, &n2,
&n3[0],&n3[1],&n3[2],&n3[3],
&n3[4],&n3[5],&n3[6],&n3[7]);
m0 = (PRInt32) n0;
m1 = (PRInt16) n1;
m2 = (PRInt16) n2;
for (int i = 0; i < 8; i++) {
m3[i] = (PRInt8) n3[i];
}
/* Optimized for speed */
if(!aIDStr) {
return PR_FALSE;
}
return (PRBool) (count == 11);
PRBool expectFormat1 = (aIDStr[0] == '{');
if(expectFormat1) aIDStr++;
PARSE_CHARS_TO_NUM(aIDStr, m0, 8);
PARSE_HYPHEN(aIDStr);
PARSE_CHARS_TO_NUM(aIDStr, m1, 4);
PARSE_HYPHEN(aIDStr);
PARSE_CHARS_TO_NUM(aIDStr, m2, 4);
PARSE_HYPHEN(aIDStr);
for(int i=0; i<2; i++)
PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
PARSE_HYPHEN(aIDStr);
while(i < 8) {
PARSE_CHARS_TO_NUM(aIDStr, m3[i], 2);
i++;
}
return expectFormat1 ? *aIDStr == '}' : PR_TRUE;
}
/*
* Returns an allocated string in {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
* format. Caller should delete [] the string.
* format. The string is allocated with PR_Malloc and should be freed by
* the caller.
*/
NS_COM char *nsID::ToString() const