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-rw-r--r--apps/eq.c97
1 files changed, 1 insertions, 96 deletions
diff --git a/apps/eq.c b/apps/eq.c
index 5977200c9c..7b7fba341d 100644
--- a/apps/eq.c
+++ b/apps/eq.c
@@ -21,105 +21,10 @@
21 21
22#include <inttypes.h> 22#include <inttypes.h>
23#include "config.h" 23#include "config.h"
24#include "dsp.h" 24#include "fixedpoint.h"
25#include "eq.h" 25#include "eq.h"
26#include "replaygain.h" 26#include "replaygain.h"
27 27
28/* Inverse gain of circular cordic rotation in s0.31 format. */
29static const long cordic_circular_gain = 0xb2458939; /* 0.607252929 */
30
31/* Table of values of atan(2^-i) in 0.32 format fractions of pi where pi = 0xffffffff / 2 */
32static const unsigned long atan_table[] = {
33 0x1fffffff, /* +0.785398163 (or pi/4) */
34 0x12e4051d, /* +0.463647609 */
35 0x09fb385b, /* +0.244978663 */
36 0x051111d4, /* +0.124354995 */
37 0x028b0d43, /* +0.062418810 */
38 0x0145d7e1, /* +0.031239833 */
39 0x00a2f61e, /* +0.015623729 */
40 0x00517c55, /* +0.007812341 */
41 0x0028be53, /* +0.003906230 */
42 0x00145f2e, /* +0.001953123 */
43 0x000a2f98, /* +0.000976562 */
44 0x000517cc, /* +0.000488281 */
45 0x00028be6, /* +0.000244141 */
46 0x000145f3, /* +0.000122070 */
47 0x0000a2f9, /* +0.000061035 */
48 0x0000517c, /* +0.000030518 */
49 0x000028be, /* +0.000015259 */
50 0x0000145f, /* +0.000007629 */
51 0x00000a2f, /* +0.000003815 */
52 0x00000517, /* +0.000001907 */
53 0x0000028b, /* +0.000000954 */
54 0x00000145, /* +0.000000477 */
55 0x000000a2, /* +0.000000238 */
56 0x00000051, /* +0.000000119 */
57 0x00000028, /* +0.000000060 */
58 0x00000014, /* +0.000000030 */
59 0x0000000a, /* +0.000000015 */
60 0x00000005, /* +0.000000007 */
61 0x00000002, /* +0.000000004 */
62 0x00000001, /* +0.000000002 */
63 0x00000000, /* +0.000000001 */
64 0x00000000, /* +0.000000000 */
65};
66
67/**
68 * Implements sin and cos using CORDIC rotation.
69 *
70 * @param phase has range from 0 to 0xffffffff, representing 0 and
71 * 2*pi respectively.
72 * @param cos return address for cos
73 * @return sin of phase, value is a signed value from LONG_MIN to LONG_MAX,
74 * representing -1 and 1 respectively.
75 */
76static long fsincos(unsigned long phase, long *cos) {
77 int32_t x, x1, y, y1;
78 unsigned long z, z1;
79 int i;
80
81 /* Setup initial vector */
82 x = cordic_circular_gain;
83 y = 0;
84 z = phase;
85
86 /* The phase has to be somewhere between 0..pi for this to work right */
87 if (z < 0xffffffff / 4) {
88 /* z in first quadrant, z += pi/2 to correct */
89 x = -x;
90 z += 0xffffffff / 4;
91 } else if (z < 3 * (0xffffffff / 4)) {
92 /* z in third quadrant, z -= pi/2 to correct */
93 z -= 0xffffffff / 4;
94 } else {
95 /* z in fourth quadrant, z -= 3pi/2 to correct */
96 x = -x;
97 z -= 3 * (0xffffffff / 4);
98 }
99
100 /* Each iteration adds roughly 1-bit of extra precision */
101 for (i = 0; i < 31; i++) {
102 x1 = x >> i;
103 y1 = y >> i;
104 z1 = atan_table[i];
105
106 /* Decided which direction to rotate vector. Pivot point is pi/2 */
107 if (z >= 0xffffffff / 4) {
108 x -= y1;
109 y += x1;
110 z -= z1;
111 } else {
112 x += y1;
113 y -= x1;
114 z += z1;
115 }
116 }
117
118 *cos = x;
119
120 return y;
121}
122
123/** 28/**
124 * Calculate first order shelving filter. Filter is not directly usable by the 29 * Calculate first order shelving filter. Filter is not directly usable by the
125 * eq_filter() function. 30 * eq_filter() function.