Added precomputed range coder probability price table.

1 files changed, 48 insertions, 0 deletions

diff --git a/src/liblzma/rangecoder/price_table_init.c b/src/liblzma/rangecoder/price_table_init.c
new file mode 100644
index 00000000..4714dfd6
--- /dev/null
+++ b/src/liblzma/rangecoder/price_table_init.c
@@ -0,0 +1,48 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       price_table_init.c
+/// \brief      Static initializations for the range encoder's prices array
+//
+//  Copyright (C) 1999-2006 Igor Pavlov
+//  Copyright (C) 2007 Lasse Collin
+//
+//  This library 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 library 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.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifdef HAVE_CONFIG_H
+#	include "range_encoder.h"
+#endif
+
+
+#define NUM_BITS (BIT_MODEL_TOTAL_BITS - MOVE_REDUCING_BITS)
+
+
+uint32_t lzma_rc_prob_prices[BIT_MODEL_TOTAL >> MOVE_REDUCING_BITS];
+
+
+extern void
+lzma_rc_init(void)
+{
+	// Initialize lzma_rc_prob_prices[].
+	for (int i = NUM_BITS - 1; i >= 0; --i) {
+		const uint32_t start = 1 << (NUM_BITS - i - 1);
+		const uint32_t end = 1 << (NUM_BITS - i);
+
+		for (uint32_t j = start; j < end; ++j) {
+			lzma_rc_prob_prices[j] = (i << BIT_PRICE_SHIFT_BITS)
+				+ (((end - j) << BIT_PRICE_SHIFT_BITS)
+				>> (NUM_BITS - i - 1));
+		}
+	}
+
+	return;
+}