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bzip2: eliminate some divisions
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parent
3f5fdc7572
commit
6a9154b6f6
@ -246,7 +246,12 @@ void fallbackSort(uint32_t* fmap,
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for (i = 0; i < 257; i++) ftab[i] = 0;
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for (i = 0; i < nblock; i++) ftab[eclass8[i]]++;
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for (i = 0; i < 256; i++) ftabCopy[i] = ftab[i];
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for (i = 1; i < 257; i++) ftab[i] += ftab[i-1];
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j = ftab[0]; /* bbox: optimized */
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for (i = 1; i < 257; i++) {
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j += ftab[i];
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ftab[i] = j;
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}
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for (i = 0; i < nblock; i++) {
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j = eclass8[i];
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@ -255,7 +260,7 @@ void fallbackSort(uint32_t* fmap,
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fmap[k] = i;
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}
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nBhtab = 2 + (nblock / 32);
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nBhtab = 2 + ((uint32_t)nblock / 32); /* bbox: unsigned div is easier */
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for (i = 0; i < nBhtab; i++) bhtab[i] = 0;
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for (i = 0; i < 256; i++) SET_BH(ftab[i]);
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@ -768,8 +773,11 @@ void mainSort(uint32_t* ptr,
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}
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/*-- Complete the initial radix sort --*/
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for (i = 1; i <= 65536; i++)
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ftab[i] += ftab[i-1];
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j = ftab[0]; /* bbox: optimized */
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for (i = 1; i <= 65536; i++) {
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j += ftab[i];
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ftab[i] = j;
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}
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s = block[0] << 8;
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i = nblock - 1;
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@ -812,19 +820,21 @@ void mainSort(uint32_t* ptr,
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{
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int32_t vv;
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/* was: int32_t h = 1; */
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/* bbox: was: int32_t h = 1; */
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/* do h = 3 * h + 1; while (h <= 256); */
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int32_t h = 364;
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uint32_t h = 364;
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do {
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h = h / 3;
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/*h = h / 3;*/
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h = (h * 171) >> 9; /* bbox: fast h/3 */
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for (i = h; i <= 255; i++) {
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vv = runningOrder[i];
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j = i;
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while (BIGFREQ(runningOrder[j-h]) > BIGFREQ(vv)) {
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runningOrder[j] = runningOrder[j-h];
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j = j - h;
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if (j <= (h - 1)) goto zero;
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if (j <= (h - 1))
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goto zero;
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}
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zero:
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runningOrder[j] = vv;
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@ -974,7 +984,6 @@ void mainSort(uint32_t* ptr,
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}
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AssertH(((bbSize-1) >> shifts) <= 65535, 1002);
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}
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}
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}
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@ -1041,7 +1050,8 @@ void BZ2_blockSort(EState* s)
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s->origPtr = -1;
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for (i = 0; i < s->nblock; i++)
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if (ptr[i] == 0) {
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s->origPtr = i; break;
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s->origPtr = i;
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break;
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};
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AssertH(s->origPtr != -1, 1003);
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@ -186,7 +186,8 @@ void generateMTFValues(EState* s)
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s->mtfFreq[BZ_RUNA]++;
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}
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if (zPend < 2) break;
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zPend = (zPend - 2) / 2;
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zPend = (uint32_t)(zPend - 2) / 2;
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/* bbox: unsigned div is easier */
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};
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zPend = 0;
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}
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@ -219,15 +220,18 @@ void generateMTFValues(EState* s)
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zPend--;
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while (1) {
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if (zPend & 1) {
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mtfv[wr] = BZ_RUNB; wr++;
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mtfv[wr] = BZ_RUNB;
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wr++;
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s->mtfFreq[BZ_RUNB]++;
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} else {
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mtfv[wr] = BZ_RUNA; wr++;
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mtfv[wr] = BZ_RUNA;
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wr++;
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s->mtfFreq[BZ_RUNA]++;
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}
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if (zPend < 2)
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break;
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zPend = (zPend - 2) / 2;
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zPend = (uint32_t)(zPend - 2) / 2;
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/* bbox: unsigned div is easier */
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};
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zPend = 0;
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}
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@ -297,7 +301,7 @@ void sendMTFValues(EState* s)
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if (ge > gs
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&& nPart != nGroups && nPart != 1
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&& ((nGroups - nPart) % 2 == 1)
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&& ((nGroups - nPart) % 2 == 1) /* bbox: can this be replaced by x & 1? */
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) {
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aFreq -= s->mtfFreq[ge];
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ge--;
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@ -183,6 +183,8 @@ void BZ2_hbMakeCodeLengths(uint8_t *len,
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for (i = 1; i <= alphaSize; i++) {
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j = weight[i] >> 8;
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/* bbox: yes, it is a signed division.
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* don't replace with shift! */
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j = 1 + (j / 2);
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weight[i] = j << 8;
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}
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