From 641998c3e1ecc8b598fe0eb051fab8b9535c291b Mon Sep 17 00:00:00 2001
From: Lasse Collin <lasse.collin@tukaani.org>
Date: Mon, 24 Mar 2008 16:38:40 +0200
Subject: Replaced the range decoder optimization that used arithmetic right
 shift with as fast version that doesn't need arithmetic right shift. Removed
 the related check from configure.ac.

---
 src/liblzma/rangecoder/range_decoder.h | 53 ++++++++++------------------------
 1 file changed, 16 insertions(+), 37 deletions(-)

(limited to 'src/liblzma/rangecoder')

diff --git a/src/liblzma/rangecoder/range_decoder.h b/src/liblzma/rangecoder/range_decoder.h
index a6a92b0b..62162448 100644
--- a/src/liblzma/rangecoder/range_decoder.h
+++ b/src/liblzma/rangecoder/range_decoder.h
@@ -121,26 +121,15 @@ do { \
 } while (0)
 
 
-#ifdef HAVE_ARITHMETIC_RSHIFT
-#	define rc_decode_direct(dest, count) \
-	do { \
-		rc_normalize(); \
-		rc.range >>= 1; \
-		rc.code -= rc.range; \
-		rc_bound = (uint32_t)((int32_t)(rc.code) >> 31); \
-		dest = (dest << 1) + (rc_bound + 1); \
-		rc.code += rc.range & rc_bound; \
-	} while (--count > 0)
-#else
-#	define rc_decode_direct(dest, count) \
-	do { \
-		rc_normalize(); \
-		rc.range >>= 1; \
-		rc_bound = (rc.code - rc.range) >> 31; \
-		rc.code -= rc.range & (rc_bound - 1); \
-		dest = ((dest) << 1) | (1 - rc_bound);\
-	} while (--count > 0)
-#endif
+#define rc_decode_direct(dest, count) \
+do { \
+	rc_normalize(); \
+	rc.range >>= 1; \
+	rc.code -= rc.range; \
+	rc_bound = UINT32_C(0) - (rc.code >> 31); \
+	rc.code += rc.range & rc_bound; \
+	dest = (dest << 1) + (rc_bound + 1); \
+} while (--count > 0)
 
 
 // Dummy versions don't update prob or dest.
@@ -155,23 +144,13 @@ do { \
 } while (0)
 
 
-#ifdef HAVE_ARITHMETIC_RSHIFT
-#	define rc_decode_direct_dummy(count) \
-	do { \
-		rc_normalize(); \
-		rc.range >>= 1; \
-		rc.code -= rc.range; \
-		rc.code += rc.range & ((uint32_t)((int32_t)(rc.code) >> 31)); \
-	} while (--count > 0)
-#else
-#	define rc_decode_direct_dummy(count) \
-	do { \
-		rc_normalize(); \
-		rc.range >>= 1; \
-		rc_bound = (rc.code - rc.range) >> 31; \
-		rc.code -= rc.range & (rc_bound - 1); \
-	} while (--count > 0)
-#endif
+#define rc_decode_direct_dummy(count) \
+do { \
+	rc_normalize(); \
+	rc.range >>= 1; \
+	rc.code -= rc.range; \
+	rc.code += rc.range & (UINT32_C(0) - (rc.code >> 31)); \
+} while (--count > 0)
 
 
 ///////////////////////
-- 
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