From ee62faee085fe04ed657626a2320a5140989746c Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@fb.com>
Date: Fri, 20 Oct 2017 12:05:00 -0700
Subject: minor refactor
reduce variable scope
remove one macro usage
---
lib/lz4opt.h | 63 +++++++++++++++++++++++++++++++++---------------------------
1 file changed, 35 insertions(+), 28 deletions(-)
diff --git a/lib/lz4opt.h b/lib/lz4opt.h
index 7d487a7..48862f2 100644
--- a/lib/lz4opt.h
+++ b/lib/lz4opt.h
@@ -265,13 +265,18 @@ static int LZ4HC_compress_optimal (
/* set prices using matches found for rPos = 0 */
{ size_t matchNb;
for (matchNb = 0; matchNb < nb_matches_initial; matchNb++) {
- size_t mlen = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH;
- best_mlen = matches[matchNb].len; /* necessarily < sufficient_len < LZ4_OPT_NUM */
- for ( ; mlen <= best_mlen ; mlen++) {
+ int mlen = (matchNb>0) ? matches[matchNb-1].len+1 : MINMATCH;
+ int const matchML = matches[matchNb].len; /* necessarily < sufficient_len < LZ4_OPT_NUM */
+ int const offset = matches[matchNb].off;
+ assert(matchML < LZ4_OPT_NUM);
+ for ( ; mlen <= matchML ; mlen++) {
size_t const cost = LZ4HC_sequencePrice(llen, mlen);
- SET_PRICE(mlen, mlen, matches[matchNb].off, 0, cost); /* updates last_match_pos and opt[pos] */
+ opt[mlen].mlen = mlen;
+ opt[mlen].off = offset;
+ opt[mlen].litlen = (int)llen;
+ opt[mlen].price = (int)cost;
} } }
- assert(last_match_pos >= MINMATCH);
+ last_match_pos = matches[nb_matches_initial-1].len;
/* check further positions */
for (cur = 1; cur <= last_match_pos; cur++) {
@@ -308,17 +313,14 @@ static int LZ4HC_compress_optimal (
{ size_t matchNb;
for (matchNb = 0; matchNb < nb_matches; matchNb++) {
size_t ml = (matchNb>0) ? (size_t)matches[matchNb-1].len+1 : MINMATCH;
- best_mlen = (cur + matches[matchNb].len < LZ4_OPT_NUM) ?
+ size_t const matchML = (cur + matches[matchNb].len < LZ4_OPT_NUM) ?
(size_t)matches[matchNb].len : LZ4_OPT_NUM - cur;
- for ( ; ml <= best_mlen ; ml++) {
+ for ( ; ml <= matchML ; ml++) {
size_t ll, price;
if (opt[cur].mlen == 1) {
ll = opt[cur].litlen;
- if (cur > ll)
- price = opt[cur - ll].price + LZ4HC_sequencePrice(ll, ml);
- else
- price = LZ4HC_sequencePrice(ll, ml);
+ price = ((cur > ll) ? opt[cur - ll].price : 0) + LZ4HC_sequencePrice(ll, ml);
} else {
ll = 0;
price = opt[cur].price + LZ4HC_sequencePrice(0, ml);
@@ -327,7 +329,7 @@ static int LZ4HC_compress_optimal (
if (cur + ml > last_match_pos || price < (size_t)opt[cur + ml].price) {
SET_PRICE(cur + ml, ml, matches[matchNb].off, ll, price);
} } } }
- } /* for (cur = 1; cur <= last_match_pos; cur++) */
+ } /* for (cur = 1; cur <= last_match_pos; cur++) */
best_mlen = opt[last_match_pos].mlen;
best_off = opt[last_match_pos].off;
@@ -337,7 +339,6 @@ encode: /* cur, last_match_pos, best_mlen, best_off must be set */
assert(cur < LZ4_OPT_NUM);
assert(last_match_pos >= 1); /* == 1 when only one candidate */
opt[0].mlen = 1;
- DEBUGLOG(6, "sequence reverse traversal");
{ int candidate_pos = (int)cur;
int selected_matchLength = (int)best_mlen;
int selected_offset = (int)best_off;
@@ -347,31 +348,37 @@ encode: /* cur, last_match_pos, best_mlen, best_off must be set */
assert(next_matchLength > 0); /* note : can be 1, means literal */
opt[candidate_pos].mlen = selected_matchLength;
opt[candidate_pos].off = selected_offset;
- DEBUGLOG(6, "rPos:%3i, matchLength:%3i", candidate_pos, selected_matchLength);
selected_matchLength = next_matchLength;
selected_offset = next_offset;
if (next_matchLength > candidate_pos) break; /* last match elected, first match to encode */
candidate_pos -= next_matchLength;
} }
- /* encode all recorded sequences */
- cur = 0;
- while (cur < last_match_pos) {
- int const ml = opt[cur].mlen;
- int const offset = opt[cur].off;
- if (ml == 1) { ip++; cur++; continue; }
- assert(ml >= MINMATCH);
- cur += ml;
- assert((offset >= 1) && (offset <=65535));
- if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) ) return 0;
- }
+ /* encode all recorded sequences in order */
+ { size_t rPos = 0; /* relative position (to ip) */
+ while (rPos < last_match_pos) {
+ int const ml = opt[rPos].mlen;
+ int const offset = opt[rPos].off;
+ if (ml == 1) { ip++; rPos++; continue; } /* literal */
+ rPos += ml;
+ assert(ml >= MINMATCH);
+ assert((offset >= 1) && (offset <=65535));
+ if ( LZ4HC_encodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) ) /* updates ip, op and anchor */
+ return 0; /* error */
+ } }
} /* while (ip < mflimit) */
/* Encode Last Literals */
{ int lastRun = (int)(iend - anchor);
- if ((limit) && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize)) return 0; /* Check output limit */
- if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
- else *op++ = (BYTE)(lastRun<<ML_BITS);
+ if ( (limit)
+ && (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize))
+ return 0; /* Check output limit */
+ if (lastRun>=(int)RUN_MASK) {
+ *op++=(RUN_MASK<<ML_BITS);
+ lastRun-=RUN_MASK;
+ for (; lastRun > 254 ; lastRun-=255) *op++ = 255;
+ *op++ = (BYTE) lastRun;
+ } else *op++ = (BYTE)(lastRun<<ML_BITS);
memcpy(op, anchor, iend - anchor);
op += iend-anchor;
}
--
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