f16727ebb
Denys Vlasenko
2010-10-30
Subject
decompress_bunzip2: code shrink ~5 bytes
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archival/libunarchive/decompress_bunzip2.c+13 -12
| @@ -153,6 +153,7 @@ static int get_next_block(bunzip_data *bd) | |
| struct group_data *hufGroup; | |
| int dbufCount, dbufSize, groupCount, *base, *limit, selector, | |
| i, j, t, runPos, symCount, symTotal, nSelectors, byteCount[256]; | |
| + | int runCnt = runCnt; /* for compiler */ |
| uint8_t uc, symToByte[256], mtfSymbol[256], *selectors; | |
| uint32_t *dbuf; | |
| unsigned origPtr; | |
| @@ -242,19 +243,19 @@ static int get_next_block(bunzip_data *bd) | |
| uint8_t length[MAX_SYMBOLS]; | |
| /* 8 bits is ALMOST enough for temp[], see below */ | |
| unsigned temp[MAX_HUFCODE_BITS+1]; | |
| - | int minLen, maxLen, pp; |
| + | int minLen, maxLen, pp, len_m1; |
| /* Read Huffman code lengths for each symbol. They're stored in | |
| a way similar to mtf; record a starting value for the first symbol, | |
| - | and an offset from the previous value for everys symbol after that. |
| + | and an offset from the previous value for every symbol after that. |
| (Subtracting 1 before the loop and then adding it back at the end is | |
| an optimization that makes the test inside the loop simpler: symbol | |
| length 0 becomes negative, so an unsigned inequality catches it.) */ | |
| - | t = get_bits(bd, 5) - 1; |
| + | len_m1 = get_bits(bd, 5) - 1; |
| for (i = 0; i < symCount; i++) { | |
| for (;;) { | |
| int two_bits; | |
| - | if ((unsigned)t > (MAX_HUFCODE_BITS-1)) |
| + | if ((unsigned)len_m1 > (MAX_HUFCODE_BITS-1)) |
| return RETVAL_DATA_ERROR; | |
| /* If first bit is 0, stop. Else second bit indicates whether | |
| @@ -267,11 +268,11 @@ static int get_next_block(bunzip_data *bd) | |
| } | |
| /* Add one if second bit 1, else subtract 1. Avoids if/else */ | |
| - | t += (((two_bits+1) & 2) - 1); |
| + | len_m1 += (((two_bits+1) & 2) - 1); |
| } | |
| /* Correct for the initial -1, to get the final symbol length */ | |
| - | length[i] = t + 1; |
| + | length[i] = len_m1 + 1; |
| } | |
| /* Find largest and smallest lengths in this group */ | |
| @@ -337,8 +338,8 @@ static int get_next_block(bunzip_data *bd) | |
| t += temp_i; | |
| base[++i] = pp - t; | |
| } | |
| - | limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */ |
| limit[maxLen] = pp + temp[maxLen] - 1; | |
| + | limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */ |
| base[minLen] = 0; | |
| } | |
| @@ -418,7 +419,7 @@ static int get_next_block(bunzip_data *bd) | |
| /* If this is the start of a new run, zero out counter */ | |
| if (runPos == 0) { | |
| runPos = 1; | |
| - | t = 0; |
| + | runCnt = 0; |
| } | |
| /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at | |
| @@ -428,7 +429,7 @@ static int get_next_block(bunzip_data *bd) | |
| the basic or 0/1 method (except all bits 0, which would use no | |
| symbols, but a run of length 0 doesn't mean anything in this | |
| context). Thus space is saved. */ | |
| - | t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ |
| + | runCnt += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ |
| if (runPos < dbufSize) runPos <<= 1; | |
| goto end_of_huffman_loop; | |
| } | |
| @@ -439,10 +440,10 @@ static int get_next_block(bunzip_data *bd) | |
| literal used is the one at the head of the mtfSymbol array.) */ | |
| if (runPos != 0) { | |
| uint8_t tmp_byte; | |
| - | if (dbufCount + t >= dbufSize) return RETVAL_DATA_ERROR; |
| + | if (dbufCount + runCnt >= dbufSize) return RETVAL_DATA_ERROR; |
| tmp_byte = symToByte[mtfSymbol[0]]; | |
| - | byteCount[tmp_byte] += t; |
| - | while (--t >= 0) dbuf[dbufCount++] = tmp_byte; |
| + | byteCount[tmp_byte] += runCnt; |
| + | while (--runCnt >= 0) dbuf[dbufCount++] = (uint32_t)tmp_byte; |
| runPos = 0; | |
| } | |