File: [local] / src / usr.bin / sndiod / dsp.c (download)
Revision 1.21, Mon Apr 22 14:11:35 2024 UTC (3 weeks, 6 days ago) by ratchov
Branch: MAIN
CVS Tags: HEAD
Changes since 1.20: +29 -27 lines
sndiod: Use the channel mapping code of aucat
For now sndiod uses only a subset of the available channel mappings.
It gives the same result as the previous one, but having the same
in both programs makes code review and testing easier.
|
/* $OpenBSD: dsp.c,v 1.21 2024/04/22 14:11:35 ratchov Exp $ */
/*
* Copyright (c) 2008-2012 Alexandre Ratchov <alex@caoua.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <string.h>
#include "dsp.h"
#include "utils.h"
const int aparams_ctltovol[128] = {
0, 65536, 68109, 70783,
73562, 76450, 79451, 82570,
85812, 89181, 92682, 96321,
100102, 104032, 108116, 112361,
116772, 121356, 126121, 131072,
136218, 141566, 147123, 152899,
158902, 165140, 171624, 178361,
185364, 192641, 200204, 208064,
216232, 224721, 233544, 242713,
252241, 262144, 272436, 283131,
294247, 305799, 317804, 330281,
343247, 356723, 370728, 385282,
400408, 416128, 432465, 449443,
467088, 485425, 504482, 524288,
544871, 566262, 588493, 611597,
635608, 660561, 686495, 713446,
741455, 770564, 800816, 832255,
864929, 898885, 934175, 970850,
1008965, 1048576, 1089742, 1132525,
1176987, 1223194, 1271216, 1321123,
1372989, 1426892, 1482910, 1541128,
1601632, 1664511, 1729858, 1797771,
1868350, 1941700, 2017930, 2097152,
2179485, 2265049, 2353974, 2446389,
2542432, 2642246, 2745978, 2853783,
2965821, 3082257, 3203264, 3329021,
3459716, 3595542, 3736700, 3883400,
4035859, 4194304, 4358969, 4530099,
4707947, 4892777, 5084864, 5284492,
5491957, 5707567, 5931642, 6164513,
6406527, 6658043, 6919432, 7191084,
7473400, 7766800, 8071719, 8388608
};
const int resamp_filt[RESAMP_LENGTH / RESAMP_STEP + 1] = {
0, 0, 3, 9, 22, 42, 73, 116,
174, 248, 341, 454, 589, 749, 934, 1148,
1392, 1666, 1974, 2316, 2693, 3107, 3560, 4051,
4582, 5154, 5766, 6420, 7116, 7853, 8632, 9451,
10311, 11210, 12148, 13123, 14133, 15178, 16253, 17359,
18491, 19647, 20824, 22018, 23226, 24443, 25665, 26888,
28106, 29315, 30509, 31681, 32826, 33938, 35009, 36033,
37001, 37908, 38744, 39502, 40174, 40750, 41223, 41582,
41819, 41925, 41890, 41704, 41358, 40842, 40147, 39261,
38176, 36881, 35366, 33623, 31641, 29411, 26923, 24169,
21140, 17827, 14222, 10317, 6105, 1580, -3267, -8440,
-13944, -19785, -25967, -32492, -39364, -46584, -54153, -62072,
-70339, -78953, -87911, -97209, -106843, -116806, -127092, -137692,
-148596, -159795, -171276, -183025, -195029, -207271, -219735, -232401,
-245249, -258259, -271407, -284670, -298021, -311434, -324880, -338329,
-351750, -365111, -378378, -391515, -404485, -417252, -429775, -442015,
-453930, -465477, -476613, -487294, -497472, -507102, -516137, -524527,
-532225, -539181, -545344, -550664, -555090, -558571, -561055, -562490,
-562826, -562010, -559990, -556717, -552139, -546205, -538866, -530074,
-519779, -507936, -494496, -479416, -462652, -444160, -423901, -401835,
-377923, -352132, -324425, -294772, -263143, -229509, -193847, -156134,
-116348, -74474, -30494, 15601, 63822, 114174, 166661, 221283,
278037, 336916, 397911, 461009, 526194, 593446, 662741, 734054,
807354, 882608, 959779, 1038826, 1119706, 1202370, 1286768, 1372846,
1460546, 1549808, 1640566, 1732753, 1826299, 1921130, 2017169, 2114336,
2212550, 2311723, 2411770, 2512598, 2614116, 2716228, 2818836, 2921841,
3025142, 3128636, 3232218, 3335782, 3439219, 3542423, 3645282, 3747687,
3849526, 3950687, 4051059, 4150530, 4248987, 4346320, 4442415, 4537163,
4630453, 4722177, 4812225, 4900493, 4986873, 5071263, 5153561, 5233668,
5311485, 5386917, 5459872, 5530259, 5597992, 5662986, 5725160, 5784436,
5840739, 5893999, 5944148, 5991122, 6034862, 6075313, 6112422, 6146142,
6176430, 6203247, 6226559, 6246335, 6262551, 6275185, 6284220, 6289647,
6291456, 6289647, 6284220, 6275185, 6262551, 6246335, 6226559, 6203247,
6176430, 6146142, 6112422, 6075313, 6034862, 5991122, 5944148, 5893999,
5840739, 5784436, 5725160, 5662986, 5597992, 5530259, 5459872, 5386917,
5311485, 5233668, 5153561, 5071263, 4986873, 4900493, 4812225, 4722177,
4630453, 4537163, 4442415, 4346320, 4248987, 4150530, 4051059, 3950687,
3849526, 3747687, 3645282, 3542423, 3439219, 3335782, 3232218, 3128636,
3025142, 2921841, 2818836, 2716228, 2614116, 2512598, 2411770, 2311723,
2212550, 2114336, 2017169, 1921130, 1826299, 1732753, 1640566, 1549808,
1460546, 1372846, 1286768, 1202370, 1119706, 1038826, 959779, 882608,
807354, 734054, 662741, 593446, 526194, 461009, 397911, 336916,
278037, 221283, 166661, 114174, 63822, 15601, -30494, -74474,
-116348, -156134, -193847, -229509, -263143, -294772, -324425, -352132,
-377923, -401835, -423901, -444160, -462652, -479416, -494496, -507936,
-519779, -530074, -538866, -546205, -552139, -556717, -559990, -562010,
-562826, -562490, -561055, -558571, -555090, -550664, -545344, -539181,
-532225, -524527, -516137, -507102, -497472, -487294, -476613, -465477,
-453930, -442015, -429775, -417252, -404485, -391515, -378378, -365111,
-351750, -338329, -324880, -311434, -298021, -284670, -271407, -258259,
-245249, -232401, -219735, -207271, -195029, -183025, -171276, -159795,
-148596, -137692, -127092, -116806, -106843, -97209, -87911, -78953,
-70339, -62072, -54153, -46584, -39364, -32492, -25967, -19785,
-13944, -8440, -3267, 1580, 6105, 10317, 14222, 17827,
21140, 24169, 26923, 29411, 31641, 33623, 35366, 36881,
38176, 39261, 40147, 40842, 41358, 41704, 41890, 41925,
41819, 41582, 41223, 40750, 40174, 39502, 38744, 37908,
37001, 36033, 35009, 33938, 32826, 31681, 30509, 29315,
28106, 26888, 25665, 24443, 23226, 22018, 20824, 19647,
18491, 17359, 16253, 15178, 14133, 13123, 12148, 11210,
10311, 9451, 8632, 7853, 7116, 6420, 5766, 5154,
4582, 4051, 3560, 3107, 2693, 2316, 1974, 1666,
1392, 1148, 934, 749, 589, 454, 341, 248,
174, 116, 73, 42, 22, 9, 3, 0,
0
};
/*
* Generate a string corresponding to the encoding in par,
* return the length of the resulting string.
*/
int
aparams_enctostr(struct aparams *par, char *ostr)
{
char *p = ostr;
*p++ = par->sig ? 's' : 'u';
if (par->bits > 9)
*p++ = '0' + par->bits / 10;
*p++ = '0' + par->bits % 10;
if (par->bps > 1) {
*p++ = par->le ? 'l' : 'b';
*p++ = 'e';
if (par->bps != APARAMS_BPS(par->bits) ||
par->bits < par->bps * 8) {
*p++ = par->bps + '0';
if (par->bits < par->bps * 8) {
*p++ = par->msb ? 'm' : 'l';
*p++ = 's';
*p++ = 'b';
}
}
}
*p++ = '\0';
return p - ostr - 1;
}
/*
* Parse an encoding string, examples: s8, u8, s16, s16le, s24be ...
* set *istr to the char following the encoding. Return the number
* of bytes consumed.
*/
int
aparams_strtoenc(struct aparams *par, char *istr)
{
char *p = istr;
int i, sig, bits, le, bps, msb;
#define IS_SEP(c) \
(((c) < 'a' || (c) > 'z') && \
((c) < 'A' || (c) > 'Z') && \
((c) < '0' || (c) > '9'))
/*
* get signedness
*/
if (*p == 's') {
sig = 1;
} else if (*p == 'u') {
sig = 0;
} else
return 0;
p++;
/*
* get number of bits per sample
*/
bits = 0;
for (i = 0; i < 2; i++) {
if (*p < '0' || *p > '9')
break;
bits = (bits * 10) + *p - '0';
p++;
}
if (bits < BITS_MIN || bits > BITS_MAX)
return 0;
bps = APARAMS_BPS(bits);
msb = 1;
le = ADATA_LE;
/*
* get (optional) endianness
*/
if (p[0] == 'l' && p[1] == 'e') {
le = 1;
p += 2;
} else if (p[0] == 'b' && p[1] == 'e') {
le = 0;
p += 2;
} else if (IS_SEP(*p)) {
goto done;
} else
return 0;
/*
* get (optional) number of bytes
*/
if (*p >= '0' && *p <= '9') {
bps = *p - '0';
if (bps < (bits + 7) / 8 ||
bps > (BITS_MAX + 7) / 8)
return 0;
p++;
/*
* get (optional) alignment
*/
if (p[0] == 'm' && p[1] == 's' && p[2] == 'b') {
msb = 1;
p += 3;
} else if (p[0] == 'l' && p[1] == 's' && p[2] == 'b') {
msb = 0;
p += 3;
} else if (IS_SEP(*p)) {
goto done;
} else
return 0;
} else if (!IS_SEP(*p))
return 0;
done:
par->msb = msb;
par->sig = sig;
par->bits = bits;
par->bps = bps;
par->le = le;
return p - istr;
}
/*
* Initialise parameters structure with the defaults natively supported
* by the machine.
*/
void
aparams_init(struct aparams *par)
{
par->bps = sizeof(adata_t);
par->bits = ADATA_BITS;
par->le = ADATA_LE;
par->sig = 1;
par->msb = 0;
}
/*
* log the given format/channels/encoding
*/
void
aparams_log(struct aparams *par)
{
char enc[ENCMAX];
aparams_enctostr(par, enc);
log_puts(enc);
}
/*
* return true if encoding corresponds to what we store in adata_t
*/
int
aparams_native(struct aparams *par)
{
return par->sig &&
par->bps == sizeof(adata_t) &&
par->bits == ADATA_BITS &&
(par->bps == 1 || par->le == ADATA_LE) &&
(par->bits == par->bps * 8 || !par->msb);
}
/*
* Return the number of input and output frame that would be consumed
* by resamp_do(p, *icnt, *ocnt).
*/
void
resamp_getcnt(struct resamp *p, int *icnt, int *ocnt)
{
long long idiff, odiff;
int cdiff;
cdiff = p->oblksz - p->diff;
idiff = (long long)*icnt * p->oblksz;
odiff = (long long)*ocnt * p->iblksz;
if (odiff - idiff >= cdiff)
*ocnt = (idiff + cdiff + p->iblksz - 1) / p->iblksz;
else
*icnt = (odiff + p->diff) / p->oblksz;
}
/*
* Resample the given number of frames. The number of output frames
* must match the corresponding number of input frames. Either always
* use icnt and ocnt such that:
*
* icnt * oblksz = ocnt * iblksz
*
* or use resamp_getcnt() to calculate the proper numbers.
*/
void
resamp_do(struct resamp *p, adata_t *in, adata_t *out, int icnt, int ocnt)
{
unsigned int nch;
adata_t *idata;
unsigned int oblksz;
unsigned int ifr;
int s, ds, diff;
adata_t *odata;
unsigned int iblksz;
unsigned int ofr;
unsigned int c;
int64_t f[NCHAN_MAX];
adata_t *ctxbuf, *ctx;
unsigned int ctx_start;
int q, qi, qf, n;
/*
* Partially copy structures into local variables, to avoid
* unnecessary indirections; this also allows the compiler to
* order local variables more "cache-friendly".
*/
idata = in;
odata = out;
diff = p->diff;
iblksz = p->iblksz;
oblksz = p->oblksz;
ctxbuf = p->ctx;
ctx_start = p->ctx_start;
nch = p->nch;
ifr = icnt;
ofr = ocnt;
/*
* Start conversion.
*/
#ifdef DEBUG
if (log_level >= 4) {
log_puts("resamp: copying ");
log_puti(ifr);
log_puts(" -> ");
log_putu(ofr);
log_puts(" frames, diff = ");
log_puti(diff);
log_puts("\n");
}
#endif
for (;;) {
if (diff >= oblksz) {
if (ifr == 0)
break;
ctx_start = (ctx_start - 1) & (RESAMP_NCTX - 1);
ctx = ctxbuf + ctx_start;
for (c = nch; c > 0; c--) {
*ctx = *idata++;
ctx += RESAMP_NCTX;
}
diff -= oblksz;
ifr--;
} else {
if (ofr == 0)
break;
for (c = 0; c < nch; c++)
f[c] = 0;
q = diff * p->filt_step;
n = ctx_start;
while (q < RESAMP_LENGTH) {
qi = q >> RESAMP_STEP_BITS;
qf = q & (RESAMP_STEP - 1);
s = resamp_filt[qi];
ds = resamp_filt[qi + 1] - s;
s += (int64_t)qf * ds >> RESAMP_STEP_BITS;
ctx = ctxbuf;
for (c = 0; c < nch; c++) {
f[c] += (int64_t)ctx[n] * s;
ctx += RESAMP_NCTX;
}
q += p->filt_cutoff;
n = (n + 1) & (RESAMP_NCTX - 1);
}
for (c = 0; c < nch; c++) {
s = f[c] >> RESAMP_BITS;
s = (int64_t)s * p->filt_cutoff >> RESAMP_BITS;
#if ADATA_BITS == 16
/*
* In 16-bit mode, we've no room for filter
* overshoots, so we need to clip the signal
* to avoid 16-bit integers to wrap around.
* In 24-bit mode, samples may exceed the
* [-1:1] range. Later, cmap_add() will clip
* them, so no need to clip them here as well.
*/
if (s >= ADATA_UNIT)
s = ADATA_UNIT - 1;
else if (s < -ADATA_UNIT)
s = -ADATA_UNIT;
#endif
*odata++ = s;
}
diff += iblksz;
ofr--;
}
}
p->diff = diff;
p->ctx_start = ctx_start;
#ifdef DEBUG
if (ifr != 0) {
log_puts("resamp_do: ");
log_puti(ifr);
log_puts(": too many input frames\n");
panic();
}
if (ofr != 0) {
log_puts("resamp_do: ");
log_puti(ofr);
log_puts(": too many output frames\n");
panic();
}
#endif
}
static unsigned int
uint_gcd(unsigned int a, unsigned int b)
{
unsigned int r;
while (b > 0) {
r = a % b;
a = b;
b = r;
}
return a;
}
/*
* initialize resampler with ibufsz/obufsz factor and "nch" channels
*/
void
resamp_init(struct resamp *p, unsigned int iblksz,
unsigned int oblksz, int nch)
{
unsigned int g;
/*
* reduce iblksz/oblksz fraction
*/
g = uint_gcd(iblksz, oblksz);
iblksz /= g;
oblksz /= g;
/*
* ensure weird rates don't cause integer overflow
*/
while (iblksz > ADATA_UNIT || oblksz > ADATA_UNIT) {
iblksz >>= 1;
oblksz >>= 1;
}
p->iblksz = iblksz;
p->oblksz = oblksz;
p->diff = 0;
p->nch = nch;
p->ctx_start = 0;
memset(p->ctx, 0, sizeof(p->ctx));
if (p->iblksz < p->oblksz) {
p->filt_cutoff = RESAMP_UNIT;
p->filt_step = RESAMP_UNIT / p->oblksz;
} else {
p->filt_cutoff = (int64_t)RESAMP_UNIT * p->oblksz / p->iblksz;
p->filt_step = RESAMP_UNIT / p->iblksz;
}
#ifdef DEBUG
if (log_level >= 3) {
log_puts("resamp: ");
log_putu(iblksz);
log_puts("/");
log_putu(oblksz);
log_puts("\n");
}
#endif
}
/*
* encode "todo" frames from native to foreign encoding
*/
void
enc_do(struct conv *p, unsigned char *in, unsigned char *out, int todo)
{
unsigned int f;
adata_t *idata;
unsigned int s;
unsigned int oshift;
unsigned int obias;
unsigned int obps;
unsigned int i;
unsigned char *odata;
int obnext;
int osnext;
#ifdef DEBUG
if (log_level >= 4) {
log_puts("enc: copying ");
log_putu(todo);
log_puts(" frames\n");
}
#endif
/*
* Partially copy structures into local variables, to avoid
* unnecessary indirections; this also allows the compiler to
* order local variables more "cache-friendly".
*/
idata = (adata_t *)in;
odata = out;
oshift = p->shift;
obias = p->bias;
obps = p->bps;
obnext = p->bnext;
osnext = p->snext;
/*
* Start conversion.
*/
odata += p->bfirst;
for (f = todo * p->nch; f > 0; f--) {
/* convert adata to u32 */
s = (int)*idata++ + ADATA_UNIT;
s <<= 32 - ADATA_BITS;
/* convert u32 to uN */
s >>= oshift;
/* convert uN to sN */
s -= obias;
/* packetize sN */
for (i = obps; i > 0; i--) {
*odata = (unsigned char)s;
s >>= 8;
odata += obnext;
}
odata += osnext;
}
}
/*
* store "todo" frames of silence in foreign encoding
*/
void
enc_sil_do(struct conv *p, unsigned char *out, int todo)
{
unsigned int f;
unsigned int s;
unsigned int oshift;
int obias;
unsigned int obps;
unsigned int i;
unsigned char *odata;
int obnext;
int osnext;
#ifdef DEBUG
if (log_level >= 4) {
log_puts("enc: silence ");
log_putu(todo);
log_puts(" frames\n");
}
#endif
/*
* Partially copy structures into local variables, to avoid
* unnecessary indirections; this also allows the compiler to
* order local variables more "cache-friendly".
*/
odata = out;
oshift = p->shift;
obias = p->bias;
obps = p->bps;
obnext = p->bnext;
osnext = p->snext;
/*
* Start conversion.
*/
odata += p->bfirst;
for (f = todo * p->nch; f > 0; f--) {
s = ((1U << 31) >> oshift) - obias;
for (i = obps; i > 0; i--) {
*odata = (unsigned char)s;
s >>= 8;
odata += obnext;
}
odata += osnext;
}
}
/*
* initialize encoder from native to foreign encoding
*/
void
enc_init(struct conv *p, struct aparams *par, int nch)
{
p->nch = nch;
p->bps = par->bps;
if (par->msb) {
p->shift = 32 - par->bps * 8;
} else {
p->shift = 32 - par->bits;
}
if (par->sig) {
p->bias = (1U << 31) >> p->shift;
} else {
p->bias = 0;
}
if (!par->le) {
p->bfirst = par->bps - 1;
p->bnext = -1;
p->snext = 2 * par->bps;
} else {
p->bfirst = 0;
p->bnext = 1;
p->snext = 0;
}
#ifdef DEBUG
if (log_level >= 3) {
log_puts("enc: ");
aparams_log(par);
log_puts(", ");
log_puti(p->nch);
log_puts(" channels\n");
}
#endif
}
/*
* decode "todo" frames from foreign to native encoding
*/
void
dec_do(struct conv *p, unsigned char *in, unsigned char *out, int todo)
{
unsigned int f;
unsigned int ibps;
unsigned int i;
unsigned int s = 0xdeadbeef;
unsigned char *idata;
int ibnext;
int isnext;
unsigned int ibias;
unsigned int ishift;
adata_t *odata;
#ifdef DEBUG
if (log_level >= 4) {
log_puts("dec: copying ");
log_putu(todo);
log_puts(" frames\n");
}
#endif
/*
* Partially copy structures into local variables, to avoid
* unnecessary indirections; this also allows the compiler to
* order local variables more "cache-friendly".
*/
idata = in;
odata = (adata_t *)out;
ibps = p->bps;
ibnext = p->bnext;
ibias = p->bias;
ishift = p->shift;
isnext = p->snext;
/*
* Start conversion.
*/
idata += p->bfirst;
for (f = todo * p->nch; f > 0; f--) {
for (i = ibps; i > 0; i--) {
s <<= 8;
s |= *idata;
idata += ibnext;
}
idata += isnext;
s += ibias;
s <<= ishift;
s >>= 32 - ADATA_BITS;
*odata++ = s - ADATA_UNIT;
}
}
/*
* initialize decoder from foreign to native encoding
*/
void
dec_init(struct conv *p, struct aparams *par, int nch)
{
p->bps = par->bps;
p->nch = nch;
if (par->msb) {
p->shift = 32 - par->bps * 8;
} else {
p->shift = 32 - par->bits;
}
if (par->sig) {
p->bias = (1U << 31) >> p->shift;
} else {
p->bias = 0;
}
if (par->le) {
p->bfirst = par->bps - 1;
p->bnext = -1;
p->snext = 2 * par->bps;
} else {
p->bfirst = 0;
p->bnext = 1;
p->snext = 0;
}
#ifdef DEBUG
if (log_level >= 3) {
log_puts("dec: ");
aparams_log(par);
log_puts(", ");
log_puti(p->nch);
log_puts(" channels\n");
}
#endif
}
/*
* mix "todo" input frames on the output with the given volume
*/
void
cmap_add(struct cmap *p, void *in, void *out, int vol, int todo)
{
adata_t *idata, *odata;
int i, j, nch, istart, inext, onext, ostart, y, v;
#ifdef DEBUG
if (log_level >= 4) {
log_puts("cmap: adding ");
log_puti(todo);
log_puts(" frames\n");
}
#endif
idata = in;
odata = out;
ostart = p->ostart;
onext = p->onext;
istart = p->istart;
inext = p->inext;
nch = p->nch;
v = vol;
/*
* map/mix input on the output
*/
for (i = todo; i > 0; i--) {
odata += ostart;
idata += istart;
for (j = nch; j > 0; j--) {
y = *odata + ADATA_MUL(*idata, v);
if (y >= ADATA_UNIT)
y = ADATA_UNIT - 1;
else if (y < -ADATA_UNIT)
y = -ADATA_UNIT;
*odata = y;
idata++;
odata++;
}
odata += onext;
idata += inext;
}
}
/*
* overwrite output with "todo" input frames with the given volume
*/
void
cmap_copy(struct cmap *p, void *in, void *out, int vol, int todo)
{
adata_t *idata, *odata;
int i, j, nch, istart, inext, onext, ostart, v;
#ifdef DEBUG
if (log_level >= 4) {
log_puts("cmap: copying ");
log_puti(todo);
log_puts(" frames\n");
}
#endif
idata = in;
odata = out;
ostart = p->ostart;
onext = p->onext;
istart = p->istart;
inext = p->inext;
nch = p->nch;
v = vol;
/*
* copy to the output buffer
*/
for (i = todo; i > 0; i--) {
idata += istart;
odata += ostart;
for (j = nch; j > 0; j--) {
*odata = ADATA_MUL(*idata, v);
odata++;
idata++;
}
odata += onext;
idata += inext;
}
}
/*
* initialize channel mapper, to map a subset of input channel range
* into a subset of the output channel range
*/
void
cmap_init(struct cmap *p,
int imin, int imax, int isubmin, int isubmax,
int omin, int omax, int osubmin, int osubmax)
{
int inch, onch, nch;
/*
* Ignore channels outside of the available sets
*/
if (isubmin < imin)
isubmin = imin;
if (isubmax > imax)
isubmax = imax;
if (osubmin < omin)
osubmin = omin;
if (osubmax > omax)
osubmax = omax;
/*
* Shrink the input or the output subset to make both subsets of
* the same size
*/
inch = isubmax - isubmin + 1;
onch = osubmax - osubmin + 1;
nch = (inch < onch) ? inch : onch;
isubmax = isubmin + nch - 1;
osubmax = osubmin + nch - 1;
p->ostart = osubmin - omin;
p->onext = omax - osubmax;
p->istart = isubmin - imin;
p->inext = imax - isubmax;
p->nch = nch;
#ifdef DEBUG
if (log_level >= 3) {
log_puts("cmap: nch = ");
log_puti(p->nch);
log_puts(", ostart = ");
log_puti(p->ostart);
log_puts(", onext = ");
log_puti(p->onext);
log_puts(", istart = ");
log_puti(p->istart);
log_puts(", inext = ");
log_puti(p->inext);
log_puts("\n");
}
#endif
}
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