[src/trunk]: src/sys/dev/audio audio(4): Rework AUDIO_GETOOFFS.

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

details:   https://anonhg.NetBSD.org/src/rev/e953064b0e45
branches:  trunk
changeset: 365717:e953064b0e45
user:      isaki <isaki%NetBSD.org@localhost>
date:      Wed Apr 20 07:11:13 2022 +0000

description:
audio(4): Rework AUDIO_GETOOFFS.
- Count .samples/.deltablks in blocks.  It makes .deltablks integer wrap
  around safe.
- Remove suspicious one block offset from .offset.  I added the offset
  because it was observed so on NetBSD7.  But according to manpage, it
  should not be.  And it looks fine without the offset.
- Related to that, remove a comment in AUDIO_WSEEK.
  Limit the user-visible buffer to usrbuf only.

diffstat:

 sys/dev/audio/audio.c    |  39 ++++++++++++++++++---------------------
 sys/dev/audio/audiodef.h |  11 ++++++++---
 2 files changed, 26 insertions(+), 24 deletions(-)

diffs (142 lines):

diff -r de02ebbbf31e -r e953064b0e45 sys/dev/audio/audio.c
--- a/sys/dev/audio/audio.c     Wed Apr 20 06:05:22 2022 +0000
+++ b/sys/dev/audio/audio.c     Wed Apr 20 07:11:13 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: audio.c,v 1.126 2022/04/20 06:05:22 isaki Exp $        */
+/*     $NetBSD: audio.c,v 1.127 2022/04/20 07:11:13 isaki Exp $        */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -181,7 +181,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: audio.c,v 1.126 2022/04/20 06:05:22 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: audio.c,v 1.127 2022/04/20 07:11:13 isaki Exp $");
 
 #ifdef _KERNEL_OPT
 #include "audio.h"
@@ -2985,7 +2985,7 @@
        audio_encoding_t *ae;
        audio_format_query_t *query;
        u_int stamp;
-       u_int offs;
+       u_int offset;
        int val;
        int index;
        int error;
@@ -3104,28 +3104,23 @@
                }
                mutex_enter(sc->sc_lock);
                mutex_enter(sc->sc_intr_lock);
-               /* figure out where next DMA will start */
-               stamp = track->usrbuf_stamp;
-               offs = track->usrbuf.head;
+               /* figure out where next transfer will start */
+               stamp = track->stamp;
+               offset = track->usrbuf.head;
                mutex_exit(sc->sc_intr_lock);
                mutex_exit(sc->sc_lock);
 
-               ao->samples = stamp;
-               ao->deltablks = (stamp / track->usrbuf_blksize) -
-                   (track->usrbuf_stamp_last / track->usrbuf_blksize);
-               track->usrbuf_stamp_last = stamp;
-               offs = rounddown(offs, track->usrbuf_blksize)
-                   + track->usrbuf_blksize;
-               if (offs >= track->usrbuf.capacity)
-                       offs -= track->usrbuf.capacity;
-               ao->offset = offs;
-
+               /* samples will overflow soon but is as per spec. */
+               ao->samples = stamp * track->usrbuf_blksize;
+               ao->deltablks = stamp - track->last_stamp;
+               ao->offset = offset;
                TRACET(2, track, "%s samples=%u deltablks=%u offset=%u",
                    pre, ao->samples, ao->deltablks, ao->offset);
+
+               track->last_stamp = stamp;
                break;
 
        case AUDIO_WSEEK:
-               /* XXX return value does not include outbuf one. */
                track = file->ptrack;
                if (track) {
                        val = track->usrbuf.used;
@@ -4964,8 +4959,6 @@
        count = uimin(usrbuf->used, track->usrbuf_blksize) / framesize;
        bytes = count * framesize;
 
-       track->usrbuf_stamp += bytes;
-
        if (usrbuf->head + bytes < usrbuf->capacity) {
                memcpy((uint8_t *)input->mem + auring_tail(input) * framesize,
                    (uint8_t *)usrbuf->mem + usrbuf->head,
@@ -5060,6 +5053,8 @@
                track->outputcounter += track->outbuf.used - track_count_0;
        }
 
+       track->stamp++;
+
 #if defined(AUDIO_DEBUG)
        if (audiodebug >= 3) {
                struct audio_track_debugbuf m;
@@ -6311,6 +6306,8 @@
        track->outbuf.used = 0;
 
        /* Clear counters. */
+       track->stamp = 0;
+       track->last_stamp = 0;
        track->dropframes = 0;
 
        audio_track_lock_exit(track);
@@ -7773,7 +7770,7 @@
 
        if (ptrack) {
                pi->seek = ptrack->usrbuf.used;
-               pi->samples = ptrack->usrbuf_stamp;
+               pi->samples = ptrack->stamp * ptrack->usrbuf_blksize;
                pi->eof = ptrack->eofcounter;
                pi->error = (ptrack->dropframes != 0) ? 1 : 0;
                pi->open = 1;
@@ -7784,7 +7781,7 @@
 
        if (rtrack) {
                ri->seek = audio_track_readablebytes(rtrack);
-               ri->samples = rtrack->usrbuf_stamp;
+               ri->samples = rtrack->stamp * rtrack->usrbuf_blksize;
                ri->eof = 0;
                ri->error = (rtrack->dropframes != 0) ? 1 : 0;
                ri->open = 1;
diff -r de02ebbbf31e -r e953064b0e45 sys/dev/audio/audiodef.h
--- a/sys/dev/audio/audiodef.h  Wed Apr 20 06:05:22 2022 +0000
+++ b/sys/dev/audio/audiodef.h  Wed Apr 20 07:11:13 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: audiodef.h,v 1.17 2022/04/20 06:05:22 isaki Exp $      */
+/*     $NetBSD: audiodef.h,v 1.18 2022/04/20 07:11:13 isaki Exp $      */
 
 /*
  * Copyright (C) 2017 Tetsuya Isaki. All rights reserved.
@@ -121,8 +121,6 @@
        u_int           usrbuf_blksize; /* usrbuf block size in bytes */
        struct uvm_object *uobj;
        bool            mmapped;        /* device is mmap()-ed */
-       u_int           usrbuf_stamp;   /* transferred bytes from/to stage */
-       u_int           usrbuf_stamp_last; /* last stamp */
        u_int           usrbuf_usedhigh;/* high water mark in bytes */
        u_int           usrbuf_usedlow; /* low water mark in bytes */
 
@@ -162,6 +160,13 @@
        u_int           volume;
 #endif
 
+       /*
+        * For AUDIO_GET[IO]OFFS.
+        * No locks are required for these.
+        */
+       u_int           stamp;          /* number of transferred blocks */
+       u_int           last_stamp;
+
        audio_trackmixer_t *mixer;      /* connected track mixer */
 
        /* Sequence number picked up by track mixer. */