/**
* Encode a difference -0x10ffff..0x10ffff in 1..4 bytes
* and return a packed integer with them.
*
* The encoding favors small absolute differences with short encodings
* to compress runs of same-script characters.
*
* Optimized version with unrolled loops and fewer floating-point operations
* than the standard packDiff().
*
* @param diff difference value -0x10ffff..0x10ffff
* @return
* 0x010000zz for 1-byte sequence zz
* 0x0200yyzz for 2-byte sequence yy zz
* 0x03xxyyzz for 3-byte sequence xx yy zz
* 0xwwxxyyzz for 4-byte sequence ww xx yy zz (ww>0x03)
*/
static int32_t
packDiff(int32_t diff) {
int32_t result, m;
U_ASSERT(!DIFF_IS_SINGLE(diff)); /* assume we won't be called where diff==BOCU1_REACH_NEG_1=-64 */
if(diff>=BOCU1_REACH_NEG_1) {
/* mostly positive differences, and single-byte negative ones */
#if 0 /* single-byte case handled in macros, see below */
if(diff<=BOCU1_REACH_POS_1) {
/* single byte */
return 0x01000000|(BOCU1_MIDDLE+diff);
} else
#endif
if(diff<=BOCU1_REACH_POS_2) {
/* two bytes */
diff-=BOCU1_REACH_POS_1+1;
result=0x02000000;
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
result|=BOCU1_TRAIL_TO_BYTE(m);
result|=(BOCU1_START_POS_2+diff)<<8;
} else if(diff<=BOCU1_REACH_POS_3) {
/* three bytes */
diff-=BOCU1_REACH_POS_2+1;
result=0x03000000;
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
result|=BOCU1_TRAIL_TO_BYTE(m);
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
result|=BOCU1_TRAIL_TO_BYTE(m)<<8;
result|=(BOCU1_START_POS_3+diff)<<16;
} else {
/* four bytes */
diff-=BOCU1_REACH_POS_3+1;
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
result=BOCU1_TRAIL_TO_BYTE(m);
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
result|=BOCU1_TRAIL_TO_BYTE(m)<<8;
/*
* We know that / and % would deliver quotient 0 and rest=diff.
* Avoid division and modulo for performance.
*/
result|=BOCU1_TRAIL_TO_BYTE(diff)<<16;
result|=((uint32_t)BOCU1_START_POS_4)<<24;
}
} else {
/* two- to four-byte negative differences */
if(diff>=BOCU1_REACH_NEG_2) {
/* two bytes */
diff-=BOCU1_REACH_NEG_1;
result=0x02000000;
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result|=BOCU1_TRAIL_TO_BYTE(m);
result|=(BOCU1_START_NEG_2+diff)<<8;
} else if(diff>=BOCU1_REACH_NEG_3) {
/* three bytes */
diff-=BOCU1_REACH_NEG_2;
result=0x03000000;
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result|=BOCU1_TRAIL_TO_BYTE(m);
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result|=BOCU1_TRAIL_TO_BYTE(m)<<8;
result|=(BOCU1_START_NEG_3+diff)<<16;
} else {
/* four bytes */
diff-=BOCU1_REACH_NEG_3;
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result=BOCU1_TRAIL_TO_BYTE(m);
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result|=BOCU1_TRAIL_TO_BYTE(m)<<8;
/*
* We know that NEGDIVMOD would deliver
* quotient -1 and rest=diff+BOCU1_TRAIL_COUNT.
* Avoid division and modulo for performance.
*/
m=diff+BOCU1_TRAIL_COUNT;
result|=BOCU1_TRAIL_TO_BYTE(m)<<16;
result|=BOCU1_MIN<<24;
}
}
return result;
}
static void U_CALLCONV
_Bocu1FromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
UErrorCode *pErrorCode) {
UConverter *cnv;
const UChar *source, *sourceLimit;
uint8_t *target;
int32_t targetCapacity;
int32_t *offsets;
int32_t prev, c, diff;
int32_t sourceIndex, nextSourceIndex;
/* set up the local pointers */
cnv=pArgs->converter;
source=pArgs->source;
sourceLimit=pArgs->sourceLimit;
target=(uint8_t *)pArgs->target;
targetCapacity=(int32_t)(pArgs->targetLimit-pArgs->target);
offsets=pArgs->offsets;
/* get the converter state from UConverter */
c=cnv->fromUChar32;
prev=(int32_t)cnv->fromUnicodeStatus;
if(prev==0) {
prev=BOCU1_ASCII_PREV;
}
/* sourceIndex=-1 if the current character began in the previous buffer */
sourceIndex= c==0 ? 0 : -1;
nextSourceIndex=0;
/* conversion loop */
if(c!=0 && targetCapacity>0) {
goto getTrail;
}
fastSingle:
/* fast loop for single-byte differences */
/* use only one loop counter variable, targetCapacity, not also source */
diff=(int32_t)(sourceLimit-source);
if(targetCapacity>diff) {
targetCapacity=diff;
}
while(targetCapacity>0 && (c=*source)<0x3000) {
if(c<=0x20) {
if(c!=0x20) {
prev=BOCU1_ASCII_PREV;
}
*target++=(uint8_t)c;
*offsets++=nextSourceIndex++;
++source;
--targetCapacity;
} else {
diff=c-prev;
if(DIFF_IS_SINGLE(diff)) {
prev=BOCU1_SIMPLE_PREV(c);
*target++=(uint8_t)PACK_SINGLE_DIFF(diff);
*offsets++=nextSourceIndex++;
++source;
--targetCapacity;
} else {
break;
}
}
}
/* restore real values */
targetCapacity=(int32_t)((const uint8_t *)pArgs->targetLimit-target);
sourceIndex=nextSourceIndex; /* wrong if offsets==NULL but does not matter */
/* regular loop for all cases */
while(source<sourceLimit) {
if(targetCapacity>0) {
c=*source++;
++nextSourceIndex;
if(c<=0x20) {
/*
* ISO C0 control & space:
* Encode directly for MIME compatibility,
* and reset state except for space, to not disrupt compression.
*/
if(c!=0x20) {
prev=BOCU1_ASCII_PREV;
}
*target++=(uint8_t)c;
*offsets++=sourceIndex;
--targetCapacity;
sourceIndex=nextSourceIndex;
continue;
}
if(U16_IS_LEAD(c)) {
getTrail:
if(source<sourceLimit) {
/* test the following code unit */
UChar trail=*source;
if(U16_IS_TRAIL(trail)) {
++source;
++nextSourceIndex;
c=U16_GET_SUPPLEMENTARY(c, trail);
}
} else {
/* no more input */
c=-c; /* negative lead surrogate as "incomplete" indicator to avoid c=0 everywhere else */
break;
}
}
/*
* all other Unicode code points c==U+0021..U+10ffff
* are encoded with the difference c-prev
*
* a new prev is computed from c,
* placed in the middle of a 0x80-block (for most small scripts) or
* in the middle of the Unihan and Hangul blocks
* to statistically minimize the following difference
*/
diff=c-prev;
prev=BOCU1_PREV(c);
if(DIFF_IS_SINGLE(diff)) {
*target++=(uint8_t)PACK_SINGLE_DIFF(diff);
*offsets++=sourceIndex;
--targetCapacity;
sourceIndex=nextSourceIndex;
if(c<0x3000) {
goto fastSingle;
}
} else if(DIFF_IS_DOUBLE(diff) && 2<=targetCapacity) {
/* optimize 2-byte case */
int32_t m;
if(diff>=0) {
diff-=BOCU1_REACH_POS_1+1;
m=diff%BOCU1_TRAIL_COUNT;
diff/=BOCU1_TRAIL_COUNT;
diff+=BOCU1_START_POS_2;
} else {
diff-=BOCU1_REACH_NEG_1;
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
diff+=BOCU1_START_NEG_2;
}
*target++=(uint8_t)diff;
*target++=(uint8_t)BOCU1_TRAIL_TO_BYTE(m);
*offsets++=sourceIndex;
*offsets++=sourceIndex;
targetCapacity-=2;
sourceIndex=nextSourceIndex;
} else {
int32_t length; /* will be 2..4 */
diff=packDiff(diff);
length=BOCU1_LENGTH_FROM_PACKED(diff);
/* write the output character bytes from diff and length */
/* from the first if in the loop we know that targetCapacity>0 */
if(length<=targetCapacity) {
switch(length) {
/* each branch falls through to the next one */
case 4:
*target++=(uint8_t)(diff>>24);
*offsets++=sourceIndex;
U_FALLTHROUGH;
case 3:
*target++=(uint8_t)(diff>>16);
*offsets++=sourceIndex;
U_FALLTHROUGH;
case 2:
*target++=(uint8_t)(diff>>8);
*offsets++=sourceIndex;
/* case 1: handled above */
*target++=(uint8_t)diff;
*offsets++=sourceIndex;
U_FALLTHROUGH;
default:
/* will never occur */
break;
}
targetCapacity-=length;
sourceIndex=nextSourceIndex;
} else {
uint8_t *charErrorBuffer;
/*
* We actually do this backwards here:
* In order to save an intermediate variable, we output
* first to the overflow buffer what does not fit into the
* regular target.
*/
/* we know that 1<=targetCapacity<length<=4 */
length-=targetCapacity;
charErrorBuffer=(uint8_t *)cnv->charErrorBuffer;
switch(length) {
/* each branch falls through to the next one */
case 3:
*charErrorBuffer++=(uint8_t)(diff>>16);
U_FALLTHROUGH;
case 2:
*charErrorBuffer++=(uint8_t)(diff>>8);
U_FALLTHROUGH;
case 1:
*charErrorBuffer=(uint8_t)diff;
U_FALLTHROUGH;
default:
/* will never occur */
break;
}
cnv->charErrorBufferLength=(int8_t)length;
/* now output what fits into the regular target */
diff>>=8*length; /* length was reduced by targetCapacity */
switch(targetCapacity) {
/* each branch falls through to the next one */
case 3:
*target++=(uint8_t)(diff>>16);
*offsets++=sourceIndex;
U_FALLTHROUGH;
case 2:
*target++=(uint8_t)(diff>>8);
*offsets++=sourceIndex;
U_FALLTHROUGH;
case 1:
*target++=(uint8_t)diff;
*offsets++=sourceIndex;
U_FALLTHROUGH;
default:
/* will never occur */
break;
}
/* target overflow */
targetCapacity=0;
*pErrorCode=U_BUFFER_OVERFLOW_ERROR;
break;
}
}
} else {
/**
* Encode a difference -0x10ffff..0x10ffff in 1..4 bytes
* and return a packed integer with them.
*
* The encoding favors small absolut differences with short encodings
* to compress runs of same-script characters.
*
* @param diff difference value -0x10ffff..0x10ffff
* @return
* 0x010000zz for 1-byte sequence zz
* 0x0200yyzz for 2-byte sequence yy zz
* 0x03xxyyzz for 3-byte sequence xx yy zz
* 0xwwxxyyzz for 4-byte sequence ww xx yy zz (ww>0x03)
*/
U_CFUNC int32_t
packDiff(int32_t diff) {
int32_t result, m, lead, count, shift;
if(diff>=BOCU1_REACH_NEG_1) {
/* mostly positive differences, and single-byte negative ones */
if(diff<=BOCU1_REACH_POS_1) {
/* single byte */
return 0x01000000|(BOCU1_MIDDLE+diff);
} else if(diff<=BOCU1_REACH_POS_2) {
/* two bytes */
diff-=BOCU1_REACH_POS_1+1;
lead=BOCU1_START_POS_2;
count=1;
} else if(diff<=BOCU1_REACH_POS_3) {
/* three bytes */
diff-=BOCU1_REACH_POS_2+1;
lead=BOCU1_START_POS_3;
count=2;
} else {
/* four bytes */
diff-=BOCU1_REACH_POS_3+1;
lead=BOCU1_START_POS_4;
count=3;
}
} else {
/* two- and four-byte negative differences */
if(diff>=BOCU1_REACH_NEG_2) {
/* two bytes */
diff-=BOCU1_REACH_NEG_1;
lead=BOCU1_START_NEG_2;
count=1;
} else if(diff>=BOCU1_REACH_NEG_3) {
/* three bytes */
diff-=BOCU1_REACH_NEG_2;
lead=BOCU1_START_NEG_3;
count=2;
} else {
/* four bytes */
diff-=BOCU1_REACH_NEG_3;
lead=BOCU1_START_NEG_4;
count=3;
}
}
/* encode the length of the packed result */
if(count<3) {
result=(count+1)<<24;
} else /* count==3, MSB used for the lead byte */ {
result=0;
}
/* calculate trail bytes like digits in itoa() */
shift=0;
do {
NEGDIVMOD(diff, BOCU1_TRAIL_COUNT, m);
result|=BOCU1_TRAIL_TO_BYTE(m)<<shift;
shift+=8;
} while(--count>0);
/* add lead byte */
result|=(lead+diff)<<shift;
return result;
}
