Cleanup FLAC__bitmath_silog2()

- Retire 32bit variant of silog2(), since only the _wide variant is used
- Rename FLAC__bitmath_silog2_wide() to FLAC__bitmath_silog2()
- Replace existing implementation by shorter, clearer implementation
  using optimised routines from bitmath.h
- Update Copyright string to 2016 in changed files

Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
Closes: https://github.com/xiph/flac/pull/6

3 files changed, 16 insertions, 57 deletions

diff --git a/src/libFLAC/bitmath.c b/src/libFLAC/bitmath.c
index 5b58ca99..b3d797d3 100644
--- a/src/libFLAC/bitmath.c
+++ b/src/libFLAC/bitmath.c
@@ -1,6 +1,6 @@
 /* libFLAC - Free Lossless Audio Codec library
  * Copyright (C) 2001-2009  Josh Coalson
- * Copyright (C) 2011-2014  Xiph.Org Foundation
+ * Copyright (C) 2011-2016  Xiph.Org Foundation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -60,50 +60,14 @@
  * silog2(  9) = 5
  * silog2( 10) = 5
  */
-unsigned FLAC__bitmath_silog2(int v)
+unsigned FLAC__bitmath_silog2(FLAC__int64 v)
 {
-	while(1) {
-		if(v == 0) {
-			return 0;
-		}
-		else if(v > 0) {
-			unsigned l = 0;
-			while(v) {
-				l++;
-				v >>= 1;
-			}
-			return l+1;
-		}
-		else if(v == -1) {
-			return 2;
-		}
-		else {
-			v++;
-			v = -v;
-		}
-	}
-}
+	if(v == 0)
+		return 0;
 
-unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v)
-{
-	while(1) {
-		if(v == 0) {
-			return 0;
-		}
-		else if(v > 0) {
-			unsigned l = 0;
-			while(v) {
-				l++;
-				v >>= 1;
-			}
-			return l+1;
-		}
-		else if(v == -1) {
-			return 2;
-		}
-		else {
-			v++;
-			v = -v;
-		}
-	}
+	if(v == -1)
+		return 2;
+
+	v = (v < 0) ? (-(v+1)) : v;
+	return FLAC__bitmath_ilog2_wide(v)+2;
 }
diff --git a/src/libFLAC/include/private/bitmath.h b/src/libFLAC/include/private/bitmath.h
index bdd154a9..9c75f85b 100644
--- a/src/libFLAC/include/private/bitmath.h
+++ b/src/libFLAC/include/private/bitmath.h
@@ -1,6 +1,6 @@
 /* libFLAC - Free Lossless Audio Codec library
  * Copyright (C) 2001-2009  Josh Coalson
- * Copyright (C) 2011-2014  Xiph.Org Foundation
+ * Copyright (C) 2011-2016  Xiph.Org Foundation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -169,9 +169,6 @@ static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
 #endif
 }
 
-
-#ifdef FLAC__INTEGER_ONLY_LIBRARY /* Unused otherwise */
-
 static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
 {
 	FLAC__ASSERT(v > 0);
@@ -207,9 +204,7 @@ static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
 	}
 #endif
 }
-#endif
 
-unsigned FLAC__bitmath_silog2(int v);
-unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v);
+unsigned FLAC__bitmath_silog2(FLAC__int64 v);
 
 #endif
diff --git a/src/libFLAC/lpc.c b/src/libFLAC/lpc.c
index e5900ef0..dc946d47 100644
--- a/src/libFLAC/lpc.c
+++ b/src/libFLAC/lpc.c
@@ -1,6 +1,6 @@
 /* libFLAC - Free Lossless Audio Codec library
  * Copyright (C) 2000-2009  Josh Coalson
- * Copyright (C) 2011-2014  Xiph.Org Foundation
+ * Copyright (C) 2011-2016  Xiph.Org Foundation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -545,11 +545,11 @@ void FLAC__lpc_compute_residual_from_qlp_coefficients_wide(const FLAC__int32 * f
 		history = data;
 		for(j = 0; j < order; j++)
 			sum += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*(--history));
-		if(FLAC__bitmath_silog2_wide(sum >> lp_quantization) > 32) {
+		if(FLAC__bitmath_silog2(sum >> lp_quantization) > 32) {
 			fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients_wide: OVERFLOW, i=%u, sum=%" PRId64 "\n", i, (sum >> lp_quantization));
 			break;
 		}
-		if(FLAC__bitmath_silog2_wide((FLAC__int64)(*data) - (sum >> lp_quantization)) > 32) {
+		if(FLAC__bitmath_silog2((FLAC__int64)(*data) - (sum >> lp_quantization)) > 32) {
 			fprintf(stderr,"FLAC__lpc_compute_residual_from_qlp_coefficients_wide: OVERFLOW, i=%u, data=%d, sum=%" PRId64 ", residual=%" PRId64 "\n", i, *data, (int64_t)(sum >> lp_quantization), ((FLAC__int64)(*data) - (sum >> lp_quantization)));
 			break;
 		}
@@ -1062,11 +1062,11 @@ void FLAC__lpc_restore_signal_wide(const FLAC__int32 * flac_restrict residual, u
 		history = data;
 		for(j = 0; j < order; j++)
 			sum += (FLAC__int64)qlp_coeff[j] * (FLAC__int64)(*(--history));
-		if(FLAC__bitmath_silog2_wide(sum >> lp_quantization) > 32) {
+		if(FLAC__bitmath_silog2(sum >> lp_quantization) > 32) {
 			fprintf(stderr,"FLAC__lpc_restore_signal_wide: OVERFLOW, i=%u, sum=%" PRId64 "\n", i, (sum >> lp_quantization));
 			break;
 		}
-		if(FLAC__bitmath_silog2_wide((FLAC__int64)(*r) + (sum >> lp_quantization)) > 32) {
+		if(FLAC__bitmath_silog2((FLAC__int64)(*r) + (sum >> lp_quantization)) > 32) {
 			fprintf(stderr,"FLAC__lpc_restore_signal_wide: OVERFLOW, i=%u, residual=%d, sum=%" PRId64 ", data=%" PRId64 "\n", i, *r, (sum >> lp_quantization), ((FLAC__int64)(*r) + (sum >> lp_quantization)));
 			break;
 		}