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authorMaurus Cuelenaere <mcuelenaere@gmail.com>2009-07-04 13:17:58 +0000
committerMaurus Cuelenaere <mcuelenaere@gmail.com>2009-07-04 13:17:58 +0000
commitc3bc8fda8019c69c1bf9cd74539df07db527eebc (patch)
tree7bab3843bfe24cbdbb5153baba12827bcd755a72 /apps/eq.c
parent861b8d8606059de2f7527e9429dc109e8b89c03c (diff)
downloadrockbox-c3bc8fda8019c69c1bf9cd74539df07db527eebc.tar.gz
rockbox-c3bc8fda8019c69c1bf9cd74539df07db527eebc.zip
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
Diffstat (limited to 'apps/eq.c')
-rw-r--r--apps/eq.c97
1 files changed, 96 insertions, 1 deletions
diff --git a/apps/eq.c b/apps/eq.c
index 7b7fba341d..5977200c9c 100644
--- a/apps/eq.c
+++ b/apps/eq.c
@@ -21,10 +21,105 @@
#include <inttypes.h>
#include "config.h"
-#include "fixedpoint.h"
+#include "dsp.h"
#include "eq.h"
#include "replaygain.h"
+/* Inverse gain of circular cordic rotation in s0.31 format. */
+static const long cordic_circular_gain = 0xb2458939; /* 0.607252929 */
+
+/* Table of values of atan(2^-i) in 0.32 format fractions of pi where pi = 0xffffffff / 2 */
+static const unsigned long atan_table[] = {
+ 0x1fffffff, /* +0.785398163 (or pi/4) */
+ 0x12e4051d, /* +0.463647609 */
+ 0x09fb385b, /* +0.244978663 */
+ 0x051111d4, /* +0.124354995 */
+ 0x028b0d43, /* +0.062418810 */
+ 0x0145d7e1, /* +0.031239833 */
+ 0x00a2f61e, /* +0.015623729 */
+ 0x00517c55, /* +0.007812341 */
+ 0x0028be53, /* +0.003906230 */
+ 0x00145f2e, /* +0.001953123 */
+ 0x000a2f98, /* +0.000976562 */
+ 0x000517cc, /* +0.000488281 */
+ 0x00028be6, /* +0.000244141 */
+ 0x000145f3, /* +0.000122070 */
+ 0x0000a2f9, /* +0.000061035 */
+ 0x0000517c, /* +0.000030518 */
+ 0x000028be, /* +0.000015259 */
+ 0x0000145f, /* +0.000007629 */
+ 0x00000a2f, /* +0.000003815 */
+ 0x00000517, /* +0.000001907 */
+ 0x0000028b, /* +0.000000954 */
+ 0x00000145, /* +0.000000477 */
+ 0x000000a2, /* +0.000000238 */
+ 0x00000051, /* +0.000000119 */
+ 0x00000028, /* +0.000000060 */
+ 0x00000014, /* +0.000000030 */
+ 0x0000000a, /* +0.000000015 */
+ 0x00000005, /* +0.000000007 */
+ 0x00000002, /* +0.000000004 */
+ 0x00000001, /* +0.000000002 */
+ 0x00000000, /* +0.000000001 */
+ 0x00000000, /* +0.000000000 */
+};
+
+/**
+ * Implements sin and cos using CORDIC rotation.
+ *
+ * @param phase has range from 0 to 0xffffffff, representing 0 and
+ * 2*pi respectively.
+ * @param cos return address for cos
+ * @return sin of phase, value is a signed value from LONG_MIN to LONG_MAX,
+ * representing -1 and 1 respectively.
+ */
+static long fsincos(unsigned long phase, long *cos) {
+ int32_t x, x1, y, y1;
+ unsigned long z, z1;
+ int i;
+
+ /* Setup initial vector */
+ x = cordic_circular_gain;
+ y = 0;
+ z = phase;
+
+ /* The phase has to be somewhere between 0..pi for this to work right */
+ if (z < 0xffffffff / 4) {
+ /* z in first quadrant, z += pi/2 to correct */
+ x = -x;
+ z += 0xffffffff / 4;
+ } else if (z < 3 * (0xffffffff / 4)) {
+ /* z in third quadrant, z -= pi/2 to correct */
+ z -= 0xffffffff / 4;
+ } else {
+ /* z in fourth quadrant, z -= 3pi/2 to correct */
+ x = -x;
+ z -= 3 * (0xffffffff / 4);
+ }
+
+ /* Each iteration adds roughly 1-bit of extra precision */
+ for (i = 0; i < 31; i++) {
+ x1 = x >> i;
+ y1 = y >> i;
+ z1 = atan_table[i];
+
+ /* Decided which direction to rotate vector. Pivot point is pi/2 */
+ if (z >= 0xffffffff / 4) {
+ x -= y1;
+ y += x1;
+ z -= z1;
+ } else {
+ x += y1;
+ y -= x1;
+ z += z1;
+ }
+ }
+
+ *cos = x;
+
+ return y;
+}
+
/**
* Calculate first order shelving filter. Filter is not directly usable by the
* eq_filter() function.