From c3bc8fda8019c69c1bf9cd74539df07db527eebc Mon Sep 17 00:00:00 2001
From: Maurus Cuelenaere <mcuelenaere@gmail.com>
Date: Sat, 4 Jul 2009 13:17:58 +0000
Subject: Revert "Consolidate all fixed point math routines in one library
 (FS#10400) by Jeffrey Goode"

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21635 a1c6a512-1295-4272-9138-f99709370657
---
 apps/replaygain.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 179 insertions(+), 2 deletions(-)

(limited to 'apps/replaygain.c')

diff --git a/apps/replaygain.c b/apps/replaygain.c
index b398afc294..90944f91d0 100644
--- a/apps/replaygain.c
+++ b/apps/replaygain.c
@@ -30,11 +30,188 @@
 #include "metadata.h"
 #include "debug.h"
 #include "replaygain.h"
-#include "fixedpoint.h"
+
+/* The fixed point math routines (with the exception of fp_atof) are based
+ * on oMathFP by Dan Carter (http://orbisstudios.com).
+ */
+
+/* 12 bits of precision gives fairly accurate result, but still allows a
+ * compact implementation. The math code supports up to 13...
+ */
 
 #define FP_BITS         (12)
+#define FP_MASK         ((1 << FP_BITS) - 1)
 #define FP_ONE          (1 << FP_BITS)
+#define FP_TWO          (2 << FP_BITS)
+#define FP_HALF         (1 << (FP_BITS - 1))
+#define FP_LN2          ( 45426 >> (16 - FP_BITS))
+#define FP_LN2_INV      ( 94548 >> (16 - FP_BITS))
+#define FP_EXP_ZERO     ( 10922 >> (16 - FP_BITS))
+#define FP_EXP_ONE      (  -182 >> (16 - FP_BITS))
+#define FP_EXP_TWO      (     4 >> (16 - FP_BITS))
+#define FP_INF          (0x7fffffff)
+#define FP_LN10         (150902 >> (16 - FP_BITS))
+
+#define FP_MAX_DIGITS       (4)
+#define FP_MAX_DIGITS_INT   (10000)
+
+#define FP_FAST_MUL_DIV
+
+#ifdef FP_FAST_MUL_DIV
+
+/* These macros can easily overflow, but they are good enough for our uses,
+ * and saves some code.
+ */
+#define fp_mul(x, y) (((x) * (y)) >> FP_BITS)
+#define fp_div(x, y) (((x) << FP_BITS) / (y))
+
+#else
+
+static long fp_mul(long x, long y)
+{
+    long x_neg = 0;
+    long y_neg = 0;
+    long rc;
+
+    if ((x == 0) || (y == 0))
+    {
+        return 0;
+    }
+
+    if (x < 0)
+    {
+        x_neg = 1;
+        x = -x;
+    }
+
+    if (y < 0)
+    {
+        y_neg = 1;
+        y = -y;
+    }
+
+    rc = (((x >> FP_BITS) * (y >> FP_BITS)) << FP_BITS)
+        + (((x & FP_MASK) * (y & FP_MASK)) >> FP_BITS)
+        + ((x & FP_MASK) * (y >> FP_BITS))
+        + ((x >> FP_BITS) * (y & FP_MASK));
+
+    if ((x_neg ^ y_neg) == 1)
+    {
+        rc = -rc;
+    }
+
+    return rc;
+}
+
+static long fp_div(long x, long y)
+{
+    long x_neg = 0;
+    long y_neg = 0;
+    long shifty;
+    long rc;
+    int msb = 0;
+    int lsb = 0;
+
+    if (x == 0)
+    {
+        return 0;
+    }
+
+    if (y == 0)
+    {
+        return (x < 0) ? -FP_INF : FP_INF;
+    }
+
+    if (x < 0)
+    {
+        x_neg = 1;
+        x = -x;
+    }
+
+    if (y < 0)
+    {
+        y_neg = 1;
+        y = -y;
+    }
+
+    while ((x & BIT_N(30 - msb)) == 0)
+    {
+        msb++;
+    }
+
+    while ((y & BIT_N(lsb)) == 0)
+    {
+        lsb++;
+    }
+
+    shifty = FP_BITS - (msb + lsb);
+    rc = ((x << msb) / (y >> lsb));
 
+    if (shifty > 0)
+    {
+        rc <<= shifty;
+    }
+    else
+    {
+        rc >>= -shifty;
+    }
+
+    if ((x_neg ^ y_neg) == 1)
+    {
+        rc = -rc;
+    }
+
+    return rc;
+}
+
+#endif /* FP_FAST_MUL_DIV */
+
+static long fp_exp(long x)
+{
+    long k;
+    long z;
+    long R;
+    long xp;
+
+    if (x == 0)
+    {
+        return FP_ONE;
+    }
+
+    k = (fp_mul(abs(x), FP_LN2_INV) + FP_HALF) & ~FP_MASK;
+
+    if (x < 0)
+    {
+        k = -k;
+    }
+
+    x -= fp_mul(k, FP_LN2);
+    z = fp_mul(x, x);
+    R = FP_TWO + fp_mul(z, FP_EXP_ZERO + fp_mul(z, FP_EXP_ONE
+        + fp_mul(z, FP_EXP_TWO)));
+    xp = FP_ONE + fp_div(fp_mul(FP_TWO, x), R - x);
+
+    if (k < 0)
+    {
+        k = FP_ONE >> (-k >> FP_BITS);
+    }
+    else
+    {
+        k = FP_ONE << (k >> FP_BITS);
+    }
+
+    return fp_mul(k, xp);
+}
+
+static long fp_exp10(long x)
+{
+    if (x == 0)
+    {
+        return FP_ONE;
+    }
+
+    return fp_exp(fp_mul(FP_LN10, x));
+}
 
 static long fp_atof(const char* s, int precision)
 {
@@ -123,7 +300,7 @@ static long convert_gain(long gain)
         gain = 17 * FP_ONE;
     }
 
-    gain = fp_factor(gain, FP_BITS) << (24 - FP_BITS);
+    gain = fp_exp10(gain / 20) << (24 - FP_BITS);
 
     return gain;
 }
-- 
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