lib/uzlib/defl_static: Optimize zlib_start/finish_block.

Collapsing the two adjacent calls to outbits saves 32 bytes.

Bringing defl_static.c into lz77.c allows better inlining, saves 24 bytes.

Merge the Outbuf/uzlib_lz77_state_t structs, a minor simplification that
doesn't change code size.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

4 files changed, 44 insertions, 80 deletions

diff --git a/lib/uzlib/defl_static.c b/lib/uzlib/defl_static.c
index 529055ae8..208e9ea5d 100644
--- a/lib/uzlib/defl_static.c
+++ b/lib/uzlib/defl_static.c
@@ -52,15 +52,15 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  * having to transmit the trees.
  */
 
-static void outbits(struct Outbuf *out, unsigned long bits, int nbits)
+static void outbits(uzlib_lz77_state_t *state, unsigned long bits, int nbits)
 {
-    assert(out->noutbits + nbits <= 32);
-    out->outbits |= bits << out->noutbits;
-    out->noutbits += nbits;
-    while (out->noutbits >= 8) {
-        out->dest_write_cb(out->dest_write_data, out->outbits & 0xFF);
-        out->outbits >>= 8;
-        out->noutbits -= 8;
+    assert(state->noutbits + nbits <= 32);
+    state->outbits |= bits << state->noutbits;
+    state->noutbits += nbits;
+    while (state->noutbits >= 8) {
+        state->dest_write_cb(state->dest_write_data, state->outbits & 0xFF);
+        state->outbits >>= 8;
+        state->noutbits -= 8;
     }
 }
 
@@ -81,18 +81,18 @@ static int int_log2(int x) {
     return r;
 }
 
-void zlib_literal(struct Outbuf *out, unsigned char c)
+static void uzlib_literal(uzlib_lz77_state_t *state, unsigned char c)
 {
     if (c <= 143) {
         /* 0 through 143 are 8 bits long starting at 00110000. */
-        outbits(out, mirrorbyte(0x30 + c), 8);
+        outbits(state, mirrorbyte(0x30 + c), 8);
     } else {
         /* 144 through 255 are 9 bits long starting at 110010000. */
-        outbits(out, 1 + 2 * mirrorbyte(0x90 - 144 + c), 9);
+        outbits(state, 1 + 2 * mirrorbyte(0x90 - 144 + c), 9);
     }
 }
 
-void zlib_match(struct Outbuf *out, int distance, int len)
+static void uzlib_match(uzlib_lz77_state_t *state, int distance, int len)
 {
     assert(distance >= 1 && distance <= 32768);
     distance -= 1;
@@ -133,9 +133,9 @@ void zlib_match(struct Outbuf *out, int distance, int len)
          * 11000000.
          */
         if (lcode <= 22) {
-            outbits(out, mirrorbyte((lcode + 1) * 2), 7);
+            outbits(state, mirrorbyte((lcode + 1) * 2), 7);
         } else {
-            outbits(out, mirrorbyte(lcode + 169), 8);
+            outbits(state, mirrorbyte(lcode + 169), 8);
         }
 
         /*
@@ -144,7 +144,7 @@ void zlib_match(struct Outbuf *out, int distance, int len)
         if (thislen < 255 && x > 1) {
             int extrabits = x - 1;
             int lmin = (thislen >> extrabits) << extrabits;
-            outbits(out, thislen - lmin, extrabits);
+            outbits(state, thislen - lmin, extrabits);
         }
 
         x = int_log2(distance);
@@ -153,7 +153,7 @@ void zlib_match(struct Outbuf *out, int distance, int len)
         /*
          * Transmit the distance code. Five bits starting at 00000.
          */
-        outbits(out, mirrorbyte((x * 2 + y) * 8), 5);
+        outbits(state, mirrorbyte((x * 2 + y) * 8), 5);
 
         /*
          * Transmit the extra bits.
@@ -161,20 +161,21 @@ void zlib_match(struct Outbuf *out, int distance, int len)
         if (x > 1) {
             int dextrabits = x - 1;
             int dmin = (distance >> dextrabits) << dextrabits;
-            outbits(out, distance - dmin, dextrabits);
+            outbits(state, distance - dmin, dextrabits);
         }
     }
 }
 
-void zlib_start_block(struct Outbuf *out)
+void uzlib_start_block(uzlib_lz77_state_t *state)
 {
-//    outbits(out, 0x9C78, 16);
-    outbits(out, 1, 1); /* Final block */
-    outbits(out, 1, 2); /* Static huffman block */
+    // Final block (0b1)
+    // Static huffman block (0b01)
+    outbits(state, 3, 3);
 }
 
-void zlib_finish_block(struct Outbuf *out)
+void uzlib_finish_block(uzlib_lz77_state_t *state)
 {
-    outbits(out, 0, 7); /* close block */
-    outbits(out, 0, 7); /* Make sure all bits are flushed */
+    // Close block (0b0000000)
+    // Make sure all bits are flushed (0b0000000)
+    outbits(state, 0, 14);
 }
diff --git a/lib/uzlib/defl_static.h b/lib/uzlib/defl_static.h
deleted file mode 100644
index 7329de36e..000000000
--- a/lib/uzlib/defl_static.h
+++ /dev/null
@@ -1,43 +0,0 @@
-/*
- * Copyright (c) uzlib authors
- *
- * This software is provided 'as-is', without any express
- * or implied warranty.  In no event will the authors be
- * held liable for any damages arising from the use of
- * this software.
- *
- * Permission is granted to anyone to use this software
- * for any purpose, including commercial applications,
- * and to alter it and redistribute it freely, subject to
- * the following restrictions:
- *
- * 1. The origin of this software must not be
- *    misrepresented; you must not claim that you
- *    wrote the original software. If you use this
- *    software in a product, an acknowledgment in
- *    the product documentation would be appreciated
- *    but is not required.
- *
- * 2. Altered source versions must be plainly marked
- *    as such, and must not be misrepresented as
- *    being the original software.
- *
- * 3. This notice may not be removed or altered from
- *    any source distribution.
- */
-
-/* This files contains type declaration and prototypes for defl_static.c.
-   They may be altered/distinct from the originals used in PuTTY source
-   code. */
-
-struct Outbuf {
-    void *dest_write_data;
-    void (*dest_write_cb)(void *data, uint8_t byte);
-    unsigned long outbits;
-    int noutbits;
-};
-
-void zlib_start_block(struct Outbuf *ctx);
-void zlib_finish_block(struct Outbuf *ctx);
-void zlib_literal(struct Outbuf *ectx, unsigned char c);
-void zlib_match(struct Outbuf *ectx, int distance, int len);
diff --git a/lib/uzlib/lz77.c b/lib/uzlib/lz77.c
index 1c7a8442c..117ce50f7 100644
--- a/lib/uzlib/lz77.c
+++ b/lib/uzlib/lz77.c
@@ -11,6 +11,8 @@
 
 #include "uzlib.h"
 
+#include "defl_static.c"
+
 #define MATCH_LEN_MIN (3)
 #define MATCH_LEN_MAX (258)
 
@@ -18,8 +20,8 @@
 // hist_max should be greater than 0 a power of 2 (ie 1, 2, 4, 8, ...).
 // It's possible to pass in hist=NULL, and then the history window will be taken from the
 // src passed in to uzlib_lz77_compress (this is useful when not doing streaming compression).
-void uzlib_lz77_init(struct uzlib_lz77_state *state, uint8_t *hist, size_t hist_max) {
-    memset(&state->outbuf, 0, sizeof(state->outbuf));
+void uzlib_lz77_init(uzlib_lz77_state_t *state, uint8_t *hist, size_t hist_max) {
+    memset(state, 0, sizeof(uzlib_lz77_state_t));
     state->hist_buf = hist;
     state->hist_max = hist_max;
     state->hist_start = 0;
@@ -30,7 +32,7 @@ void uzlib_lz77_init(struct uzlib_lz77_state *state, uint8_t *hist, size_t hist_
 // Search back in the history for the maximum match of the given src data,
 // with support for searching beyond the end of the history and into the src buffer
 // (effectively the history and src buffer are concatenated).
-static size_t uzlib_lz77_search_max_match(struct uzlib_lz77_state *state, const uint8_t *src, size_t len, size_t *longest_offset) {
+static size_t uzlib_lz77_search_max_match(uzlib_lz77_state_t *state, const uint8_t *src, size_t len, size_t *longest_offset) {
     size_t longest_len = 0;
     for (size_t hist_search = 0; hist_search < state->hist_len; ++hist_search) {
         size_t match_len;
@@ -55,7 +57,7 @@ static size_t uzlib_lz77_search_max_match(struct uzlib_lz77_state *state, const
 }
 
 // Compress the given chunk of data.
-void uzlib_lz77_compress(struct uzlib_lz77_state *state, const uint8_t *src, unsigned len) {
+void uzlib_lz77_compress(uzlib_lz77_state_t *state, const uint8_t *src, unsigned len) {
     const uint8_t *top = src + len;
     while (src < top) {
         // Look for a match in the history window.
@@ -64,10 +66,10 @@ void uzlib_lz77_compress(struct uzlib_lz77_state *state, const uint8_t *src, uns
 
         // Encode the literal byte or the match.
         if (match_len == 0) {
-            zlib_literal(&state->outbuf, *src);
+            uzlib_literal(state, *src);
             match_len = 1;
         } else {
-            zlib_match(&state->outbuf, match_offset, match_len);
+            uzlib_match(state, match_offset, match_len);
         }
 
         // Push the bytes into the history buffer.
diff --git a/lib/uzlib/uzlib.h b/lib/uzlib/uzlib.h
index 80f1b2a72..030f7698c 100644
--- a/lib/uzlib/uzlib.h
+++ b/lib/uzlib/uzlib.h
@@ -42,8 +42,6 @@
 #include <stdint.h>
 #include <stdbool.h>
 
-#include "defl_static.h"
-
 #include "uzlib_conf.h"
 #if UZLIB_CONF_DEBUG_LOG
 #include <stdio.h>
@@ -135,16 +133,22 @@ int uzlib_parse_zlib_gzip_header(uzlib_uncomp_t *d, int *wbits);
 
 /* Compression API */
 
-struct uzlib_lz77_state {
-    struct Outbuf outbuf;
+typedef struct {
+    void *dest_write_data;
+    void (*dest_write_cb)(void *data, uint8_t byte);
+    unsigned long outbits;
+    int noutbits;
     uint8_t *hist_buf;
     size_t hist_max;
     size_t hist_start;
     size_t hist_len;
-};
+} uzlib_lz77_state_t;
+
+void uzlib_lz77_init(uzlib_lz77_state_t *state, uint8_t *hist, size_t hist_max);
+void uzlib_lz77_compress(uzlib_lz77_state_t *state, const uint8_t *src, unsigned len);
 
-void uzlib_lz77_init(struct uzlib_lz77_state *state, uint8_t *hist, size_t hist_max);
-void uzlib_lz77_compress(struct uzlib_lz77_state *state, const uint8_t *src, unsigned len);
+void uzlib_start_block(uzlib_lz77_state_t *state);
+void uzlib_finish_block(uzlib_lz77_state_t *state);
 
 /* Checksum API */