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authorVincent Sanders <vince@kyllikki.org>2017-01-30 15:00:38 (GMT)
committer Vincent Sanders <vince@kyllikki.org>2017-01-30 15:00:38 (GMT)
commit3db59ff9dd4257f9ee0a7c027b508bef32c2f2e3 (patch)
tree2d2fd82dde7c432a5ab61baea48f6f5174492b75
parente22e25143d985025d9c6d8811784280ee7d9302b (diff)
downloadlibnsgif-3db59ff9dd4257f9ee0a7c027b508bef32c2f2e3.tar.gz
libnsgif-3db59ff9dd4257f9ee0a7c027b508bef32c2f2e3.tar.bz2
isolate LZW initialisation
-rw-r--r--src/libnsgif.c39
1 files changed, 25 insertions, 14 deletions
diff --git a/src/libnsgif.c b/src/libnsgif.c
index 9045bbd..fe91111 100644
--- a/src/libnsgif.c
+++ b/src/libnsgif.c
@@ -222,6 +222,29 @@ static gif_result gif_clear_codes_LZW(gif_animation *gif)
/**
+ * Initialise LZW
+ *
+ * This initialises a LZW context ready to commence decompression.
+ *
+ * \param initial_code_size The size of codes used on clearing of code dictionary
+ */
+static gif_result gif_initialise_LZW(gif_animation *gif, int initial_code_size)
+{
+ lzw->set_code_size = initial_code_size;
+ lzw->code_size = lzw->set_code_size + 1;
+ lzw->clear_code = (1 << lzw->set_code_size);
+ lzw->end_code = lzw->clear_code + 1;
+ lzw->max_code_size = lzw->clear_code << 1;
+ lzw->max_code = lzw->clear_code + 2;
+ lzw->curbit = lzw->lastbit = 0;
+ lzw->last_byte = 2;
+ lzw->get_done = false;
+ lzw->direct = lzw->buf;
+
+ return gif_clear_codes_LZW(gif);
+}
+
+/**
* fill the LZW stack with decompressed data
*
* \param gif The GIF context.
@@ -1065,22 +1088,10 @@ gif_internal_decode_frame(gif_animation *gif,
}
}
gif->decoded_frame = frame;
-
- /* Initialise the LZW decoding */
- lzw->set_code_size = gif_data[0];
gif->buffer_position = (gif_data - gif->gif_data) + 1;
- /* Set our code variables */
- lzw->code_size = lzw->set_code_size + 1;
- lzw->clear_code = (1 << lzw->set_code_size);
- lzw->end_code = lzw->clear_code + 1;
- lzw->max_code_size = lzw->clear_code << 1;
- lzw->max_code = lzw->clear_code + 2;
- lzw->curbit = lzw->lastbit = 0;
- lzw->last_byte = 2;
- lzw->get_done = false;
- lzw->direct = lzw->buf;
- gif->current_error = gif_clear_codes_LZW(gif);
+ /* Initialise the LZW decoding */
+ gif->current_error = gif_initialise_LZW(gif, gif_data[0]);
if (gif->current_error != GIF_OK) {
return gif->current_error;
}