diff options
author | Michael Giacomelli <giac2000@hotmail.com> | 2010-03-05 21:49:40 +0000 |
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committer | Michael Giacomelli <giac2000@hotmail.com> | 2010-03-05 21:49:40 +0000 |
commit | 6fc422e94019ccb0f5aa4cdee8cc010b64592961 (patch) | |
tree | 2af11391be706f9124a4ad40ebc28230a086a030 /apps/codecs/libwma | |
parent | 4e797175f1b8954b60b8f1d8a7514c7c03a6d4a1 (diff) | |
download | rockbox-6fc422e94019ccb0f5aa4cdee8cc010b64592961.tar.gz rockbox-6fc422e94019ccb0f5aa4cdee8cc010b64592961.zip |
Fix red by moving fsincos back to libwma
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25036 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/codecs/libwma')
-rw-r--r-- | apps/codecs/libwma/wmafixed.c | 101 | ||||
-rw-r--r-- | apps/codecs/libwma/wmafixed.h | 3 |
2 files changed, 103 insertions, 1 deletions
diff --git a/apps/codecs/libwma/wmafixed.c b/apps/codecs/libwma/wmafixed.c index 1472ed081c..649025b53a 100644 --- a/apps/codecs/libwma/wmafixed.c +++ b/apps/codecs/libwma/wmafixed.c @@ -250,3 +250,104 @@ fixed64 fixdiv64(fixed64 x, fixed64 y) return (fixed32)(r << (PRECISION / 2)); } + + + 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. + * + * Gives at least 24 bits precision (last 2-8 bits or so are probably off) + */ + + long fsincos(unsigned long phase, fixed32 *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; + } + } + + if (cos) + *cos = x; + + return y; + } +
\ No newline at end of file diff --git a/apps/codecs/libwma/wmafixed.h b/apps/codecs/libwma/wmafixed.h index 0ecdc5cfbc..d07acb3c6c 100644 --- a/apps/codecs/libwma/wmafixed.h +++ b/apps/codecs/libwma/wmafixed.h @@ -107,4 +107,5 @@ static inline fixed32 fixmul32(fixed32 x, fixed32 y) #endif -/* get fixmul32b from codeclib */ +/* Inverse gain of circular cordic rotation in s0.31 format. */ +long fsincos(unsigned long phase, fixed32 *cos); |