flate

commit f08500976663fe63aa81e0f6bd4f421e07b8d5c1
parent e2c36cb2b784ab7ded4dcd79925bb2291058108a
Author: nsz <nszabolcs@gmail.com>
Date:   Tue,  9 Jun 2009 12:09:55 +0200

less gotos
Diffstat:
inflate.c
 | 
44
++++++++++++++------------------------------

1 file changed, 14 insertions(+), 30 deletions(-)
diff --git a/inflate.c b/inflate.c
@@ -337,26 +337,12 @@ static uint decode_symbol(State *s, Huff *huff) {
 static int decode_block(State *s, Huff *lhuff, Huff *dhuff) {
 	uchar *win = s->win;
 	uint pos = s->pos;
-	uint sym;
-	uint len;
-	uint dist;
+	uint sym = s->nclen;
+	uint len = s->lenpos;
+	uint dist = s->nclen;
 
 	switch (s->state) {
-	case DecodeBlockLenBits:
-		sym = s->nclen;
-		goto decode_lenbits;
-	case DecodeBlockDist:
-		len = s->lenpos;
-		goto decode_dist;
-	case DecodeBlockDistBits:
-		sym = s->nclen;
-		len = s->lenpos;
-		goto decode_distbits;
-	case DecodeBlockCopy:
-		dist = s->nclen;
-		len = s->lenpos;
-		goto decode_copy;
-	}
+	case DecodeBlock:
 	for (;;) {
 		sym = decode_symbol(s, lhuff);
 
@@ -376,7 +362,7 @@ static int decode_block(State *s, Huff *lhuff, Huff *dhuff) {
 					return FlateNeedInput;
 				return FlateError;
 			}
-decode_lenbits:
+	case DecodeBlockLenBits:
 			if (!fillbits_fast(&s->src, s->srcend, &s->bits, &s->nbits, lenbits[sym])) {
 				s->nclen = sym; /* using nclen to store sym */
 				s->pos = pos;
@@ -384,7 +370,7 @@ decode_lenbits:
 				return FlateNeedInput;
 			}
 			len = lenbase[sym] + getbits_fast(&s->bits, &s->nbits, lenbits[sym]);
-decode_dist:
+	case DecodeBlockDist:
 			sym = decode_symbol(s, dhuff);
 			if (sym == (uint)FlateNeedInput) {
 				s->pos = pos;
@@ -394,7 +380,7 @@ decode_dist:
 			}
 			if (sym >= Ndist)
 				return FlateError;
-decode_distbits:
+	case DecodeBlockDistBits:
 			if (!fillbits_fast(&s->src, s->srcend, &s->bits, &s->nbits, distbits[sym])) {
 				s->nclen = sym; /* using nclen to store sym */
 				s->pos = pos;
@@ -402,7 +388,6 @@ decode_distbits:
 				s->state = DecodeBlockDistBits;
 				return FlateNeedInput;
 			}
-			/* TODO: s/dist/sym/ */
 			dist = distbase[sym] + getbits_fast(&s->bits, &s->nbits, distbits[sym]);
 			/* copy match, loop unroll in common case */
 			if (pos + len < WinSize) {
@@ -425,14 +410,14 @@ decode_distbits:
 					}
 				}
 			} else { /* rare */
-decode_copy:
+	case DecodeBlockCopy:
 				while (len--) {
 					win[pos] = win[(pos - dist) & WinMask];
 					pos++;
 					if (pos == WinSize) {
 						s->pos = pos;
 						s->lenpos = len;
-						s->nclen = dist;
+						s->nclen = dist; /* using nclen to store dist */
 						s->state = DecodeBlockCopy;
 						return FlateHasOutput;
 					}
@@ -442,7 +427,9 @@ decode_copy:
 			s->pos = pos;
 			return FlateOk;
 		}
-	}
+	} /* for (;;) */
+	} /* switch () */
+	return FlateError;
 }
 
 
@@ -603,10 +590,7 @@ int inflate(State *s) {
 		case DecodeBlockDist:
 		case DecodeBlockDistBits:
 		case DecodeBlockCopy:
-			if (s->fixed)
-				n = decode_block(s, &lhuff, &dhuff);
-			else
-				n = decode_block(s, &s->lhuff, &s->dhuff);
+			n = decode_block(s, s->fixed ? &lhuff : &s->lhuff, s->fixed ? &dhuff : &s->dhuff);
 			if (n == FlateNeedInput)
 				return FlateNeedInput;
 			if (n == FlateHasOutput)
@@ -651,7 +635,7 @@ int inflate_callback(int (*r)(void *, int, void *), void *rdata, int (*w)(void *
 				free(src);
 				return FlateError;
 			}
-			s.pos = 0; /* ouch */
+			s.pos = 0; /* TODO: ouch */
 			break;
 		case FlateOk:
 			free(src);