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ICU-103 more performance in fromU() by goto _into_ the loop

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X-SVN-Rev: 1954
This commit is contained in:
Markus Scherer 2000-07-19 21:24:04 +00:00
parent aed9e41539
commit 7130aeef99
1 changed files with 25 additions and 35 deletions
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60
icu4c/source/common/ucnvmbcs.c
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@ -829,6 +829,23 @@ _MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
uint32_t value;
int32_t length;
/*
* This is another piece of ugly code:
* A goto into the loop if the converter state contains a first surrogate
* from the previous function call.
* It saves me to check in each loop iteration a check of if(c==0)
* and duplicating the trail-surrogate-handling code in the else
* branch of that check.
* I could not find any other way to get around this other than
* using a function call for the conversion and callback, which would
* be even more inefficient.
*
* Markus Scherer 2000-jul-19
*/
if(c!=0) {
goto getTrail;
}
while(source<sourceLimit) {
/*
* This following test is to see if available input would overflow the output.
@ -844,26 +861,15 @@ _MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
* a single UChar for a BMP code point or
* a matched surrogate pair for a "surrogate code point".
*/
if(c==0) {
/* there was no lead code unit (1st surrogate) before */
c=*source++;
++nextSourceIndex;
if(!UTF_IS_SURROGATE(c)) {
/* convert this BMP code point */
/* exit this condition tree */
} else if(UTF_IS_SURROGATE_FIRST(c)) {
c=*source++;
++nextSourceIndex;
if(UTF_IS_SURROGATE(c)) {
if(UTF_IS_SURROGATE_FIRST(c)) {
if(source<sourceLimit) {
/*
* I have duplicated here the code from below
* that gets the trail unit and checks for a match.
* I do not think that with pre-existing state
* in the converter I could get around duplicating this
* at all.
* (I would have to jump here from outside the loop if(c!=0).)
*
* Markus Scherer 2000-jul-17
*/
UChar trail=*source;
UChar trail;
getTrail:
/* test the following code unit */
trail=*source;
if(UTF_IS_SECOND_SURROGATE(trail)) {
++source;
++nextSourceIndex;
@ -888,22 +894,6 @@ _MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
*pErrorCode=U_ILLEGAL_CHAR_FOUND;
goto callback;
}
} else {
/* c contains a lead code unit (1st surrogate) */
UChar trail=*source;
if(UTF_IS_SECOND_SURROGATE(trail)) {
++source;
++nextSourceIndex;
c=UTF16_GET_PAIR_VALUE(c, trail);
/* convert this surrogate code point */
/* exit this condition tree */
} else {
/* this is an unmatched lead code unit (1st surrogate) */
/* callback(illegal) */
reason=UCNV_ILLEGAL;
*pErrorCode=U_ILLEGAL_CHAR_FOUND;
goto callback;
}
}
/* convert the Unicode code point in c into codepage bytes */