gzip: code shrink
Converted a few 16-bit variables and small arrays to 32-bit. Stopped pulling desc->FOO members into temporary local variables in gen_bitlen(): on register-starved arches, this is a loss, temporaries go into stack slots. Sprinkled a few "const" on pointer arguments. function old new delta pack_gzip 742 745 +3 gen_codes 101 97 -4 build_tree 886 833 -53 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/2 up/down: 3/-57) Total: -54 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
81a708393d
commit
d327c6b190
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@ -507,7 +507,7 @@ static ALWAYS_INLINE void flush_outbuf_if_32bit_optimized(void)
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* pointer, then initialize the crc shift register contents instead.
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* Return the current crc in either case.
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*/
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static void updcrc(uch * s, unsigned n)
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static void updcrc(uch *s, unsigned n)
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{
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G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
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}
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@ -610,7 +610,7 @@ static void bi_windup(void)
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* Copy a stored block to the zip file, storing first the length and its
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* one's complement if requested.
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*/
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static void copy_block(char *buf, unsigned len, int header)
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static void copy_block(const char *buf, unsigned len, int header)
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{
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bi_windup(); /* align on byte boundary */
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@ -1010,7 +1010,8 @@ struct globals2 {
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tree_desc d_desc;
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tree_desc bl_desc;
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ush bl_count[MAX_BITS + 1];
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/* was "ush", but "unsigned" results in smaller code */
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unsigned bl_count[MAX_BITS + 1];
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/* The lengths of the bit length codes are sent in order of decreasing
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* probability, to avoid transmitting the lengths for unused bit length codes.
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@ -1121,7 +1122,7 @@ static void init_block(void)
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(tree[n].Freq < tree[m].Freq \
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|| (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
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static void pqdownheap(ct_data * tree, int k)
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static void pqdownheap(const ct_data *tree, int k)
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{
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int v = G2.heap[k];
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int j = k << 1; /* left son of k */
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@ -1155,22 +1156,15 @@ static void pqdownheap(ct_data * tree, int k)
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* The length opt_len is updated; static_len is also updated if stree is
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* not null.
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*/
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static void gen_bitlen(tree_desc * desc)
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static void gen_bitlen(const tree_desc *desc)
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{
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ct_data *tree = desc->dyn_tree;
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const uint8_t *extra = desc->extra_bits;
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int base = desc->extra_base;
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int max_code = desc->max_code;
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int max_length = desc->max_length;
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ct_data *stree = desc->static_tree;
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int h; /* heap index */
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int n, m; /* iterate over the tree elements */
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int bits; /* bit length */
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int xbits; /* extra bits */
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ush f; /* frequency */
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int overflow = 0; /* number of elements with bit length too large */
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#define tree desc->dyn_tree
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int h; /* heap index */
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int n, m; /* iterate over the tree elements */
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int bits; /* bit length */
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int overflow; /* number of elements with bit length too large */
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for (bits = 0; bits <= MAX_BITS; bits++)
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for (bits = 0; bits < ARRAY_SIZE(G2.bl_count); bits++)
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G2.bl_count[bits] = 0;
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/* In a first pass, compute the optimal bit lengths (which may
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@ -1178,28 +1172,32 @@ static void gen_bitlen(tree_desc * desc)
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*/
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tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
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overflow = 0;
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for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
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ulg f; /* frequency */
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int xbits; /* extra bits */
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n = G2.heap[h];
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bits = tree[tree[n].Dad].Len + 1;
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if (bits > max_length) {
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bits = max_length;
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if (bits > desc->max_length) {
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bits = desc->max_length;
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overflow++;
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}
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tree[n].Len = (ush) bits;
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/* We overwrite tree[n].Dad which is no longer needed */
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if (n > max_code)
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if (n > desc->max_code)
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continue; /* not a leaf node */
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G2.bl_count[bits]++;
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xbits = 0;
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if (n >= base)
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xbits = extra[n - base];
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if (n >= desc->extra_base)
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xbits = desc->extra_bits[n - desc->extra_base];
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f = tree[n].Freq;
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G2.opt_len += (ulg) f *(bits + xbits);
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G2.opt_len += f * (bits + xbits);
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if (stree)
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G2.static_len += (ulg) f * (stree[n].Len + xbits);
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if (desc->static_tree)
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G2.static_len += f * (desc->static_tree[n].Len + xbits);
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}
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if (overflow == 0)
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return;
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@ -1209,14 +1207,14 @@ static void gen_bitlen(tree_desc * desc)
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/* Find the first bit length which could increase: */
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do {
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bits = max_length - 1;
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bits = desc->max_length - 1;
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while (G2.bl_count[bits] == 0)
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bits--;
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G2.bl_count[bits]--; /* move one leaf down the tree */
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G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
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G2.bl_count[max_length]--;
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G2.bl_count[desc->max_length]--;
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/* The brother of the overflow item also moves one step up,
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* but this does not affect bl_count[max_length]
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* but this does not affect bl_count[desc->max_length]
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*/
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overflow -= 2;
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} while (overflow > 0);
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@ -1226,11 +1224,11 @@ static void gen_bitlen(tree_desc * desc)
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* lengths instead of fixing only the wrong ones. This idea is taken
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* from 'ar' written by Haruhiko Okumura.)
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*/
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for (bits = max_length; bits != 0; bits--) {
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for (bits = desc->max_length; bits != 0; bits--) {
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n = G2.bl_count[bits];
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while (n != 0) {
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m = G2.heap[--h];
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if (m > max_code)
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if (m > desc->max_code)
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continue;
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if (tree[m].Len != (unsigned) bits) {
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Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
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@ -1240,6 +1238,7 @@ static void gen_bitlen(tree_desc * desc)
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n--;
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}
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}
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#undef tree
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}
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/* ===========================================================================
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@ -1250,12 +1249,13 @@ static void gen_bitlen(tree_desc * desc)
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* OUT assertion: the field code is set for all tree elements of non
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* zero code length.
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*/
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static void gen_codes(ct_data * tree, int max_code)
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static void gen_codes(ct_data *tree, int max_code)
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{
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ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
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ush code = 0; /* running code value */
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int bits; /* bit index */
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int n; /* code index */
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/* next_code[] and code used to be "ush", but "unsigned" results in smaller code */
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unsigned next_code[MAX_BITS + 1]; /* next code value for each bit length */
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unsigned code = 0; /* running code value */
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int bits; /* bit index */
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int n; /* code index */
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/* The distribution counts are first used to generate the code values
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* without bit reversal.
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@ -1307,7 +1307,7 @@ do { \
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pqdownheap(tree, SMALLEST); \
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} while (0)
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static void build_tree(tree_desc * desc)
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static void build_tree(tree_desc *desc)
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{
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ct_data *tree = desc->dyn_tree;
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ct_data *stree = desc->static_tree;
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@ -1385,10 +1385,10 @@ static void build_tree(tree_desc * desc)
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/* At this point, the fields freq and dad are set. We can now
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* generate the bit lengths.
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*/
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gen_bitlen((tree_desc *) desc);
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gen_bitlen(desc);
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/* The field len is now set, we can generate the bit codes */
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gen_codes((ct_data *) tree, max_code);
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gen_codes(tree, max_code);
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}
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/* ===========================================================================
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@ -1397,7 +1397,7 @@ static void build_tree(tree_desc * desc)
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* counts. (The contribution of the bit length codes will be added later
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* during the construction of bl_tree.)
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*/
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static void scan_tree(ct_data * tree, int max_code)
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static void scan_tree(ct_data *tree, int max_code)
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{
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int n; /* iterates over all tree elements */
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int prevlen = -1; /* last emitted length */
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@ -1449,7 +1449,7 @@ static void scan_tree(ct_data * tree, int max_code)
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* Send a literal or distance tree in compressed form, using the codes in
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* bl_tree.
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*/
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static void send_tree(ct_data * tree, int max_code)
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static void send_tree(const ct_data *tree, int max_code)
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{
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int n; /* iterates over all tree elements */
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int prevlen = -1; /* last emitted length */
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@ -1625,7 +1625,7 @@ static int ct_tally(int dist, int lc)
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/* ===========================================================================
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* Send the block data compressed using the given Huffman trees
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*/
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static void compress_block(ct_data * ltree, ct_data * dtree)
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static void compress_block(const ct_data *ltree, const ct_data *dtree)
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{
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unsigned dist; /* distance of matched string */
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int lc; /* match length or unmatched char (if dist == 0) */
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@ -1675,7 +1675,7 @@ static void compress_block(ct_data * ltree, ct_data * dtree)
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* trees or store, and output the encoded block to the zip file. This function
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* returns the total compressed length for the file so far.
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*/
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static void flush_block(char *buf, ulg stored_len, int eof)
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static void flush_block(const char *buf, ulg stored_len, int eof)
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{
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ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
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int max_blindex; /* index of last bit length code of non zero freq */
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