celp_math.c File Reference
#include <inttypes.h>
#include <limits.h>
#include <assert.h>
#include "avcodec.h"
#include "celp_math.h"

Go to the source code of this file.

Functions

int16_t ff_cos (uint16_t arg)
 fixed-point implementation of cosine in [0; PI) domain.
int ff_exp2 (uint16_t power)
 fixed-point implementation of exp2(x) in [0; 1] domain.
int ff_log2 (uint32_t value)
 Calculate log2(x).
float ff_dot_productf (const float *a, const float *b, int length)
 Return the dot product.

Variables

static const int16_t tab_cos [65]
 Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)
static const uint16_t exp2a []
static const uint16_t exp2b []
static const uint16_t tab_log2 [33]
 Table used to compute log2(x)

Function Documentation

int16_t ff_cos ( uint16_t  arg)

fixed-point implementation of cosine in [0; PI) domain.

Parameters
argfixed-point cosine argument, 0 <= arg < 0x4000
Returns
value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff

Definition at line 61 of file celp_math.c.

Referenced by ff_acelp_lsf2lsp().

float ff_dot_productf ( const float *  a,
const float *  b,
int  length 
)
int ff_exp2 ( uint16_t  power)

fixed-point implementation of exp2(x) in [0; 1] domain.

Parameters
powerargument to exp2, 0 <= power <= 0x7fff
Returns
value of (1<<20) * exp2(power / (1<<15)) 0x8000c <= result <= 0xfffea

Definition at line 71 of file celp_math.c.

int ff_log2 ( uint32_t  value)

Calculate log2(x).

Parameters
valuefunction argument, 0 < value <= 7fff ffff
Returns
value of (1<<15) * log2(value)

Definition at line 94 of file celp_math.c.

Referenced by ff_acelp_update_past_gain().

Variable Documentation

const uint16_t exp2a[]
static
Initial value:
{
0, 1435, 2901, 4400, 5931, 7496, 9096, 10730,
12400, 14106, 15850, 17632, 19454, 21315, 23216, 25160,
27146, 29175, 31249, 33368, 35534, 37747, 40009, 42320,
44682, 47095, 49562, 52082, 54657, 57289, 59979, 62727,
}

Definition at line 45 of file celp_math.c.

Referenced by ff_exp2().

const uint16_t exp2b[]
static
Initial value:
{
3, 712, 1424, 2134, 2845, 3557, 4270, 4982,
5696, 6409, 7124, 7839, 8554, 9270, 9986, 10704,
11421, 12138, 12857, 13576, 14295, 15014, 15734, 16455,
17176, 17898, 18620, 19343, 20066, 20790, 21514, 22238,
}

Definition at line 53 of file celp_math.c.

const int16_t tab_cos[65]
static
Initial value:
{
32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
-12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
-23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
-30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
}

Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)

Definition at line 33 of file celp_math.c.

Referenced by ff_cos().

const uint16_t tab_log2[33]
static
Initial value:
{
4, 1459, 2870, 4240, 5572, 6867, 8127, 9355,
10552, 11719, 12858, 13971, 15057, 16120, 17158, 18175,
19170, 20145, 21100, 22036, 22954, 23854, 24738, 25605,
26457, 27294, 28116, 28924, 29719, 30500, 31269, 32025, 32769,
}

Table used to compute log2(x)

tab_log2[i] = (1<<15) * log2(1 + i/32), i=0..32

Definition at line 86 of file celp_math.c.

Referenced by ff_log2().