[src/trunk]: src/sys/dev/ic Correct ADPCM -> linear8 conversion routine.

[isaki <isaki%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1a00b346ad90
branches:  trunk
changeset: 524928:1a00b346ad90
user:      isaki <isaki%NetBSD.org@localhost>
date:      Tue Apr 02 15:19:00 2002 +0000

description:
Correct ADPCM -> linear8 conversion routine.
Now, we can record on vs0 (but it's very noisy)

diffstat:

 sys/dev/ic/msm6258.c |  49 ++++++++++++++++++++++++++++---------------------
 1 files changed, 28 insertions(+), 21 deletions(-)

diffs (106 lines):

diff -r 1774e9ac886a -r 1a00b346ad90 sys/dev/ic/msm6258.c
--- a/sys/dev/ic/msm6258.c      Tue Apr 02 15:09:07 2002 +0000
+++ b/sys/dev/ic/msm6258.c      Tue Apr 02 15:19:00 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: msm6258.c,v 1.6 2002/03/16 09:00:42 isaki Exp $        */
+/*     $NetBSD: msm6258.c,v 1.7 2002/04/02 15:19:00 isaki Exp $        */
 
 /*
  * Copyright (c) 2001 Tetsuya Isaki. All rights reserved.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: msm6258.c,v 1.6 2002/03/16 09:00:42 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: msm6258.c,v 1.7 2002/04/02 15:19:00 isaki Exp $");
 
 #include <sys/systm.h>
 #include <sys/device.h>
@@ -55,8 +55,8 @@
 
 
 static int adpcm_estimindex[16] = {
-        125,  375,  625,  875,  1125,  1375,  1625,  1875,
-       -125, -375, -625, -875, -1125, -1375, -1625, -1875
+        1,  3,  5,  7,  9,  11,  13,  15,
+       -1, -3, -5, -7, -9, -11, -13, -15
 };
 
 static int adpcm_estim[49] = {
@@ -104,21 +104,20 @@
 
        a -= *y;
        d = adpcm_estim[(int) *x];
-       c = a * 4 * 1000;
-       c /= d;
+       c = a * 4  / d;
 
        if (c < 0) {
-               b = (unsigned char)(-c/1000);
+               b = (unsigned char)-c;
                if (b >= 8)
                        b = 7;
                b |= 0x08;
        } else {
-               b = (unsigned char)(c/1000);
+               b = (unsigned char)c;
                if (b >= 8)
                        b = 7;
        }
 
-       *y += (short)(adpcm_estimindex[b] * d / 1000);
+       *y += (short)(adpcm_estimindex[b] * d / 8);
        *x += adpcm_estimindex_correct[b];
        if (*x < 0)
                *x = 0;
@@ -154,12 +153,20 @@
 static inline void
 adpcm2pcm_step(u_char b, short *y, char *x)
 {
-       *y += (short)(adpcm_estimindex[b] * adpcm_estim[(int) *x]);
-       *x += adpcm_estimindex_correct[b];
-       if (*x < 0)
-               *x = 0;
-       else if (*x > 48)
-               *x = 48;
+       short dl;
+       short pcm = *y;
+       int estim = *x;
+
+       dl = adpcm_estim[estim] * adpcm_estimindex[b] / 8;
+       pcm += dl;
+       *y = pcm / 256;
+
+       estim += adpcm_estimindex_correct[b];
+       if (estim < 0)
+               estim = 0;
+       if (estim > 48)
+               estim = 48;
+       *x = estim;
 }
 
 /* ADPCM stream must be converted in order. */
@@ -175,17 +182,17 @@
        u_char a, b;
        int i;
 
-       for (i = 0; i < cc;) {
-               a = *p;
-               p++;
+       /* cc may be even. XXX alignment? */
+       memcpy(tmpbuf, p, cc/2);
+       for (i = 0; i < cc/2;) {
+               a = tmpbuf[i++];
                b = a & 0x0f;
                adpcm2pcm_step(b, y, x);
-               tmpbuf[i++] = *y;
+               *p++ = *y;
                b = a >> 4;
                adpcm2pcm_step(b, y, x);
-               tmpbuf[i++] = *y;
+               *p++ = *y;
        }
-       memcpy(p, tmpbuf, cc*2);
 }
 
 void