Standardize on the vi editing directives being on the first line.

[oweals/busybox.git] / archival / libunarchive / decompress_unlzma.c

diff --git a/archival/libunarchive/decompress_unlzma.c b/archival/libunarchive/decompress_unlzma.c
index fa7b37c37c422fe23429b85c2c22e63e4ba018b6..0fb1249cba6e8c5f9e43b7b3883cdf02148695fd 100644 (file)
--- a/archival/libunarchive/decompress_unlzma.c
+++ b/archival/libunarchive/decompress_unlzma.c
@@ -1,3 +1,4 @@
+/* vi: set sw=4 ts=4: */
 /*
  * Small lzma deflate implementation.
  * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
@@ -5,31 +6,154 @@
  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
  * Copyright (C) 1999-2005  Igor Pavlov
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <stdint.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <byteswap.h>
-
 #include "libbb.h"
-
 #include "unarchive.h"
 
-#include "rangecoder.h"
+#ifdef CONFIG_FEATURE_LZMA_FAST
+#  define speed_inline ATTRIBUTE_ALWAYS_INLINE
+#else
+#  define speed_inline
+#endif
+
+
+typedef struct {
+       int fd;
+       uint8_t *ptr;
+       uint8_t *buffer;
+       uint8_t *buffer_end;
+       int buffer_size;
+       uint32_t code;
+       uint32_t range;
+       uint32_t bound;
+} rc_t;
+
+
+#define RC_TOP_BITS 24
+#define RC_MOVE_BITS 5
+#define RC_MODEL_TOTAL_BITS 11
+
+
+/* Called twice: once at startup and once in rc_normalize() */
+static void rc_read(rc_t * rc)
+{
+       rc->buffer_size = read(rc->fd, rc->buffer, rc->buffer_size);
+       if (rc->buffer_size <= 0)
+               bb_error_msg_and_die("unexpected EOF");
+       rc->ptr = rc->buffer;
+       rc->buffer_end = rc->buffer + rc->buffer_size;
+}
+
+/* Called once */
+static void rc_init(rc_t * rc, int fd, int buffer_size)
+{
+       int i;
+
+       rc->fd = fd;
+       rc->buffer = xmalloc(buffer_size);
+       rc->buffer_size = buffer_size;
+       rc->buffer_end = rc->buffer + rc->buffer_size;
+       rc->ptr = rc->buffer_end;
+
+       rc->code = 0;
+       rc->range = 0xFFFFFFFF;
+       for (i = 0; i < 5; i++) {
+               if (rc->ptr >= rc->buffer_end)
+                       rc_read(rc);
+               rc->code = (rc->code << 8) | *rc->ptr++;
+       }
+}
+
+/* Called once. TODO: bb_maybe_free() */
+static ATTRIBUTE_ALWAYS_INLINE void rc_free(rc_t * rc)
+{
+       if (ENABLE_FEATURE_CLEAN_UP)
+               free(rc->buffer);
+}
+
+/* Called twice, but one callsite is in speed_inline'd rc_is_bit_0_helper() */
+static void rc_do_normalize(rc_t * rc)
+{
+       if (rc->ptr >= rc->buffer_end)
+               rc_read(rc);
+       rc->range <<= 8;
+       rc->code = (rc->code << 8) | *rc->ptr++;
+}
+static ATTRIBUTE_ALWAYS_INLINE void rc_normalize(rc_t * rc)
+{
+       if (rc->range < (1 << RC_TOP_BITS)) {
+               rc_do_normalize(rc);
+       }
+}
+
+/* Called 9 times */
+/* Why rc_is_bit_0_helper exists?
+ * Because we want to always expose (rc->code < rc->bound) to optimizer
+ */
+static speed_inline uint32_t rc_is_bit_0_helper(rc_t * rc, uint16_t * p)
+{
+       rc_normalize(rc);
+       rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
+       return rc->bound;
+}
+static ATTRIBUTE_ALWAYS_INLINE int rc_is_bit_0(rc_t * rc, uint16_t * p)
+{
+       uint32_t t = rc_is_bit_0_helper(rc, p);
+       return rc->code < t;
+}
+
+/* Called ~10 times, but very small, thus inlined */
+static speed_inline void rc_update_bit_0(rc_t * rc, uint16_t * p)
+{
+       rc->range = rc->bound;
+       *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
+}
+static speed_inline void rc_update_bit_1(rc_t * rc, uint16_t * p)
+{
+       rc->range -= rc->bound;
+       rc->code -= rc->bound;
+       *p -= *p >> RC_MOVE_BITS;
+}
+
+/* Called 4 times in unlzma loop */
+static int rc_get_bit(rc_t * rc, uint16_t * p, int *symbol)
+{
+       if (rc_is_bit_0(rc, p)) {
+               rc_update_bit_0(rc, p);
+               *symbol *= 2;
+               return 0;
+       } else {
+               rc_update_bit_1(rc, p);
+               *symbol = *symbol * 2 + 1;
+               return 1;
+       }
+}
+
+/* Called once */
+static ATTRIBUTE_ALWAYS_INLINE int rc_direct_bit(rc_t * rc)
+{
+       rc_normalize(rc);
+       rc->range >>= 1;
+       if (rc->code >= rc->range) {
+               rc->code -= rc->range;
+               return 1;
+       }
+       return 0;
+}
+
+/* Called twice */
+static speed_inline void
+rc_bit_tree_decode(rc_t * rc, uint16_t * p, int num_levels, int *symbol)
+{
+       int i = num_levels;
+
+       *symbol = 1;
+       while (i--)
+               rc_get_bit(rc, p + *symbol, symbol);
+       *symbol -= 1 << num_levels;
+}
 
 
 typedef struct {
@@ -344,4 +468,3 @@ int unlzma(int src_fd, int dst_fd)
        return 0;
 }
 
-/* vi:set ts=4: */