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Add experimental support for 24-bit arithmetic, meaning that full 

dynamic range of 24-bit hardware can be used. Offline processing like
mixing and channel mapping is done with 24-bit precision too.
This commit is contained in:
Alexandre Ratchov 2010-11-05 17:55:42 +01:00
parent 2f1ceb6662
commit bc81d0b2ea
1 changed files with 57 additions and 0 deletions
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57
aucat/aparams.h
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@ -54,15 +54,72 @@ struct aparams {
* boundary is excluded. We represent them as signed fixed point numbers
* of ADATA_BITS. We also assume that 2^(ADATA_BITS - 1) fits in a int.
*/
#ifndef ADATA_BITS
#define ADATA_BITS 16
#endif
#define ADATA_LE (BYTE_ORDER == LITTLE_ENDIAN)
#define ADATA_UNIT (1 << (ADATA_BITS - 1))
#if ADATA_BITS == 16
typedef short adata_t;
#define ADATA_MUL(x,y) (((int)(x) * (int)(y)) >> (ADATA_BITS - 1))
#define ADATA_MULDIV(x,y,z) ((int)(x) * (int)(y) / (int)(z))
#elif ADATA_BITS == 24
typedef int adata_t;
#if defined(__i386__) && defined(__GNUC__)
static inline int
fp24_mul(int x, int a)
{
int res;
asm volatile (
"imull %2\n\t"
"shrdl $23, %%edx, %%eax\n\t"
: "=a" (res)
: "a" (x), "r" (a)
: "%edx"
);
return res;
}
static inline int
fp24_muldiv(int x, int a, int b)
{
int res;
asm volatile (
"imull %2\n\t"
"idivl %3\n\t"
: "=a" (res)
: "a" (x), "d" (a), "r" (b)
);
return res;
}
#define ADATA_MUL(x,y) fp24_mul(x, y)
#define ADATA_MULDIV(x,y,z) fp24_muldiv(x, y, z);
#elif defined(__amd64__) || defined(__sparc64__)
#define ADATA_MUL(x,y) \
((int)(((long long)(x) * (long long)(y)) >> (ADATA_BITS - 1)))
#define ADATA_MULDIV(x,y,z) \
((int)((long long)(x) * (long long)(y) / (long long)(z)))
#else
#error "no 24-bit code for this architecture"
#endif
#else
#error "only 16-bit and 24-bit precisions are supported"
#endif
#define MIDI_MAXCTL 127
#define MIDI_TO_ADATA(m) (aparams_ctltovol[m] << (ADATA_BITS - 16))