From 85aad9b3972208b0e34ba0241ebb5314118ae05e Mon Sep 17 00:00:00 2001
From: Andrew Mahone <andrew.mahone@gmail.com>
Date: Wed, 9 Dec 2009 02:24:45 +0000
Subject: Extend av_log2 in codeclib into a generic for scanning for set bits,
 which can provide either log2 or leading-zero-count output, and can force
 mapping 0 input to 0 output if needed (otherwise 0 input produces undefined
 result). Replace av_log2 in lib/codeclib.h, floor_log2 and wl_min_lzc in
 libfaad/common.c and common.h, and count_leading_zeros in libalac/alac.c with
 macros using bs_generic.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@23903 a1c6a512-1295-4272-9138-f99709370657
---
 apps/codecs/libfaad/common.c    | 53 +----------------------------------------
 apps/codecs/libfaad/common.h    |  4 +---
 apps/codecs/libfaad/sbr_hfgen.c |  8 -------
 3 files changed, 2 insertions(+), 63 deletions(-)

(limited to 'apps/codecs/libfaad')

diff --git a/apps/codecs/libfaad/common.c b/apps/codecs/libfaad/common.c
index debc125b3e..e8340d318d 100644
--- a/apps/codecs/libfaad/common.c
+++ b/apps/codecs/libfaad/common.c
@@ -241,58 +241,7 @@ uint32_t random_int(void)
     return (__r1 = (t3 >> 1) | t1 ) ^ (__r2 = (t4 + t4) | t2 );
 }
 
-uint32_t ones32(uint32_t x)
-{
-    x -= ((x >> 1) & 0x55555555);
-    x = (((x >> 2) & 0x33333333) + (x & 0x33333333));
-    x = (((x >> 4) + x) & 0x0f0f0f0f);
-    x += (x >> 8);
-    x += (x >> 16);
-
-    return (x & 0x0000003f);
-}
-
-uint32_t floor_log2(uint32_t x)
-{
-#if 1
-    x |= (x >> 1);
-    x |= (x >> 2);
-    x |= (x >> 4);
-    x |= (x >> 8);
-    x |= (x >> 16);
-
-    return (ones32(x) - 1);
-#else
-    uint32_t count = 0;
-
-    while (x >>= 1)
-        count++;
-
-    return count;
-#endif
-}
-
-/* returns position of first bit that is not 0 from msb,
- * starting count at lsb */
-uint32_t wl_min_lzc(uint32_t x)
-{
-#if 1
-    x |= (x >> 1);
-    x |= (x >> 2);
-    x |= (x >> 4);
-    x |= (x >> 8);
-    x |= (x >> 16);
-
-    return (ones32(x));
-#else
-    uint32_t count = 0;
-
-    while (x >>= 1)
-        count++;
-
-    return (count + 1);
-#endif
-}
+#define floor_log2(x) bs_generic(x, BS_LOG2)
 
 #ifdef FIXED_POINT
 
diff --git a/apps/codecs/libfaad/common.h b/apps/codecs/libfaad/common.h
index ea028b1b8e..fe0d02b228 100644
--- a/apps/codecs/libfaad/common.h
+++ b/apps/codecs/libfaad/common.h
@@ -399,9 +399,7 @@ typedef real_t complex_t[2];
 /* common functions */
 uint8_t cpu_has_sse(void);
 uint32_t random_int(void);
-uint32_t ones32(uint32_t x);
-uint32_t floor_log2(uint32_t x);
-uint32_t wl_min_lzc(uint32_t x);
+#define wl_min_lzc(x) bs_generic(x, BS_LOG2|BS_0_0)
 #ifdef FIXED_POINT
 #define LOG2_MIN_INF REAL_CONST(-10000)
 int32_t log2_int(uint32_t val);
diff --git a/apps/codecs/libfaad/sbr_hfgen.c b/apps/codecs/libfaad/sbr_hfgen.c
index 4991839218..f77bbd052f 100644
--- a/apps/codecs/libfaad/sbr_hfgen.c
+++ b/apps/codecs/libfaad/sbr_hfgen.c
@@ -222,10 +222,6 @@ static void auto_correlation(sbr_info *sbr, acorr_coef *ac,
 
     exp = wl_min_lzc(mask);
 
-    /* improves accuracy */
-    if (exp > 0)
-        exp -= 1;
-
     for (j = offset; j < len + offset; j++)
     {
         real_t buf_j = ((QMF_RE(buffer[j][bd])+(1<<(exp-1)))>>exp);
@@ -292,10 +288,6 @@ static void auto_correlation(sbr_info *sbr, acorr_coef *ac, qmf_t buffer[MAX_NTS
     }
 
     exp = wl_min_lzc(mask);
-
-    /* improves accuracy */
-    if (exp > 0)
-        exp -= 1;
    
     pow2_to_exp = 1<<(exp-1);
 
-- 
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