From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Sat Oct 19 18:52:41 2019 +0200
Subject: gzip: code shrink
Patch-mainline: 6572ef6e1e4822f785b7139ef166586c444dc01e
Git-repo: https://git.busybox.net/busybox
Git-commit: de5e8dce4ffde011ece77f864ca326a9c98b50c1
References: 

huft_build() still has way too many params

function                                             old     new   delta
lit                                                    -      94     +94
dist                                                   -      94     +94
huft_build                                          1058    1054      -4
inflate_block                                       1281    1254     -27
cpdext                                                30       -     -30
cplext                                                31       -     -31
cpdist                                                60       -     -60
cplens                                                62       -     -62
------------------------------------------------------------------------------
(add/remove: 2/4 grow/shrink: 0/2 up/down: 188/-214)          Total: -26 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Egbert Eich <eich@suse.de>
---
 archival/libarchive/decompress_gunzip.c | 55 ++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 29 deletions(-)
diff --git a/archival/libarchive/decompress_gunzip.c b/archival/libarchive/decompress_gunzip.c
index 8f23a7307..6571b23d7 100644
--- a/archival/libarchive/decompress_gunzip.c
+++ b/archival/libarchive/decompress_gunzip.c
@@ -186,29 +186,26 @@ static const uint16_t mask_bits[] ALIGN2 = {
 	0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
 };
 
-/* Copy lengths for literal codes 257..285 */
-static const uint16_t cplens[] ALIGN2 = {
-	3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59,
-	67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
+/* Put lengths/offsets and extra bits in a struct of arrays
+ * to make calls to huft_build() have one fewer parameter.
+ */
+struct cp_ext {
+	uint16_t cp[31];
+	uint8_t ext[31];
 };
-
+/* Copy lengths and extra bits for literal codes 257..285 */
 /* note: see note #13 above about the 258 in this list. */
-/* Extra bits for literal codes 257..285 */
-static const uint8_t cplext[] ALIGN1 = {
-	0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5,
-	5, 5, 5, 0, 99, 99
-}; /* 99 == invalid */
-
-/* Copy offsets for distance codes 0..29 */
-static const uint16_t cpdist[] ALIGN2 = {
-	1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513,
-	769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577
+static const struct cp_ext lit = {
+	/*257 258 259 260 261 262 263 264 265 266 267 268 269 270 271  272  273  274  275  276   277   278   279   280   281   282   283    284    285 */
+	/*0   1   2   3   4   5   6   7   8   9   10  11  12  13   14   15   16   17   18   19    20    21    22    23    24    25    26     27     28     29  30 */
+	{ 3,  4,  5,  6,  7,  8,  9,  10, 11, 13, 15, 17, 19, 23,  27,  31,  35,  43,  51,  59,   67,   83,   99,  115,  131,  163,  195,   227,   258,     0, 0  },
+	{ 0,  0,  0,  0,  0,  0,  0,   0,  1,  1,  1,  1,  2,  2,   2,   2,   3,   3,   3,   3,    4,    4,    4,    4,    5,    5,    5,     5,     0,    99, 99 } /* 99 == invalid */
 };
-
-/* Extra bits for distance codes */
-static const uint8_t cpdext[] ALIGN1 = {
-	0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10,
-	11, 11, 12, 12, 13, 13
+/* Copy offsets and extra bits for distance codes 0..29 */
+static const struct cp_ext dist = {
+	/*0   1   2   3   4   5   6   7   8   9   10  11  12  13   14   15   16   17   18   19    20    21    22    23    24    25    26     27     28     29 */
+	{ 1,  2,  3,  4,  5,  7,  9,  13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577 },
+	{ 0,  0,  0,  0,  1,  1,  2,   2,  3,  3,  4,  4,  5,  5,   6,   6,   7,   7,   8,   8,    9,    9,   10,   10,   11,   11,   12,    12,    13,    13 }
 };
 
 /* Tables for deflate from PKZIP's appnote.txt. */
@@ -290,8 +287,8 @@ static unsigned fill_bitbuffer(STATE_PARAM unsigned bitbuffer, unsigned *current
  * result: starting table
  */
 static huft_t* huft_build(const unsigned *b, const unsigned n,
-			const unsigned s, const uint16_t *d,
-			const uint8_t *e, unsigned *m)
+			const unsigned s, const struct cp_ext *cp_ext,
+			unsigned *m)
 {
 	unsigned a;             /* counter for codes of length k */
 	unsigned c[BMAX + 1];   /* bit length count table */
@@ -449,8 +446,8 @@ static huft_t* huft_build(const unsigned *b, const unsigned n,
 				r.e = (unsigned char) (*p < 256 ? 16 : 15);	/* 256 is EOB code */
 				r.v.n = (unsigned short) (*p++); /* simple code is just the value */
 			} else {
-				r.e = (unsigned char) e[*p - s]; /* non-simple--look up in lists */
-				r.v.n = d[*p++ - s];
+				r.e = (unsigned char) cp_ext->ext[*p - s]; /* non-simple--look up in lists */
+				r.v.n = cp_ext->cp[*p++ - s];
 			}
 
 			/* fill code-like entries with r */
@@ -779,14 +776,14 @@ static int inflate_block(STATE_PARAM smallint *e)
 		for (; i < 288; i++) /* make a complete, but wrong code set */
 			ll[i] = 8;
 		bl = 7;
-		inflate_codes_tl = huft_build(ll, 288, 257, cplens, cplext, &bl);
+		inflate_codes_tl = huft_build(ll, 288, 257, &lit, &bl);
 		/* huft_build() never returns error here - we use known data */
 
 		/* set up distance table */
 		for (i = 0; i < 30; i++) /* make an incomplete code set */
 			ll[i] = 5;
 		bd = 5;
-		inflate_codes_td = huft_build(ll, 30, 0, cpdist, cpdext, &bd);
+		inflate_codes_td = huft_build(ll, 30, 0, &dist, &bd);
 
 		/* set up data for inflate_codes() */
 		inflate_codes_setup(PASS_STATE bl, bd);
@@ -852,7 +849,7 @@ static int inflate_block(STATE_PARAM smallint *e)
 
 		/* build decoding table for trees - single level, 7 bit lookup */
 		bl = 7;
-		inflate_codes_tl = huft_build(ll, 19, 19, NULL, NULL, &bl);
+		inflate_codes_tl = huft_build(ll, 19, 19, NULL, &bl);
 		if (!inflate_codes_tl) {
 			abort_unzip(PASS_STATE_ONLY);	/* incomplete code set */
 		}
@@ -917,12 +914,12 @@ static int inflate_block(STATE_PARAM smallint *e)
 
 		/* build the decoding tables for literal/length and distance codes */
 		bl = lbits;
-		inflate_codes_tl = huft_build(ll, nl, 257, cplens, cplext, &bl);
+		inflate_codes_tl = huft_build(ll, nl, 257, &lit, &bl);
 		if (!inflate_codes_tl) {
 			abort_unzip(PASS_STATE_ONLY);
 		}
 		bd = dbits;
-		inflate_codes_td = huft_build(ll + nl, nd, 0, cpdist, cpdext, &bd);
+		inflate_codes_td = huft_build(ll + nl, nd, 0, &dist, &bd);
 		if (!inflate_codes_td) {
 			abort_unzip(PASS_STATE_ONLY);
 		}
