Files
qemu-qemu-1/audio/mixeng_template.h
Akihiko Odaki 64abf45516 audio: Use unsigned PCM bias
Clang warns for the uint32_t clip_ instantiations because HALF cannot be
represented with mixeng_real:

[1115/2559] Compiling C object libqemuaudio.a.p/audio_mixeng.c.o
In file included from ../../qemu/audio/mixeng.c:147:
../../qemu/audio/mixeng_template.h:68:70: warning: implicit conversion from 'unsigned int' to 'float' changes value from 2147483647 to 2147483648 [-Wimplicit-const-int-float-conversion]
   68 |     return ENDIAN_CONVERT((IN_T)((v * ((mixeng_real)IN_MAX / 2.f)) + HALF));
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../../qemu/audio/mixeng_template.h:31:22: note: expanded from macro 'HALF'
   31 | #define HALF (IN_MAX >> 1)
      |                      ^
../../qemu/audio/mixeng.c:146:28: note: expanded from macro 'ENDIAN_CONVERT'
  146 | #define ENDIAN_CONVERT(v) (v)
      |                            ^
In file included from ../../qemu/audio/mixeng.c:152:
../../qemu/audio/mixeng_template.h:68:70: warning: implicit conversion from 'unsigned int' to 'float' changes value from 2147483647 to 2147483648 [-Wimplicit-const-int-float-conversion]
   68 |     return ENDIAN_CONVERT((IN_T)((v * ((mixeng_real)IN_MAX / 2.f)) + HALF));
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
../../qemu/audio/mixeng_template.h:31:22: note: expanded from macro 'HALF'
   31 | #define HALF (IN_MAX >> 1)
      |                      ^
../../qemu/audio/mixeng.c:151:36: note: expanded from macro 'ENDIAN_CONVERT'
  151 | #define ENDIAN_CONVERT(v) bswap32 (v)
      |                           ~~~~~~~~~^~
/Users/person/v/qemu/include/qemu/bswap.h:10:39: note: expanded from macro 'bswap32'
   10 | #define bswap32(_x) __builtin_bswap32(_x)
      |                                       ^~
2 warnings generated.

HALF is not the right value here anyway. IN_MAX is odd, so the integer
sample range has two middle codes. Unsigned PCM normally uses the upper
middle code as the "bias": 0x80, 0x8000, or 0x80000000. HALF is instead
defined as the lower middle code: 0x7f, 0x7fff, or 0x7fffffff.

Replace HALF with BIAS, defined as the upper middle code. This fixes the
warnings, since the value can be exactly represented with mixeng_real.

Signed-off-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20260423-audio-v1-3-e1d6b65c76f9@rsg.ci.i.u-tokyo.ac.jp>
2026-04-28 18:53:58 +04:00

153 lines
3.9 KiB
C

/*
* QEMU Mixing engine
*
* Copyright (c) 2004-2005 Vassili Karpov (malc)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* Tusen tack till Mike Nordell
* dec++'ified by Dscho
*/
#ifndef SIGNED
#define BIAS ((IN_T)1 << (SHIFT - 1))
#endif
#define ET glue (ENDIAN_CONVERSION, glue (glue (glue (_, ITYPE), BSIZE), _t))
#define IN_T glue (glue (ITYPE, BSIZE), _t)
#ifdef FLOAT_MIXENG
static inline mixeng_real glue (conv_, ET) (IN_T v)
{
IN_T nv = ENDIAN_CONVERT (v);
#ifdef RECIPROCAL
#ifdef SIGNED
return nv * (2.f / ((mixeng_real)IN_MAX - IN_MIN));
#else
return ((mixeng_real)nv - BIAS) * (1.f / BIAS);
#endif
#else /* !RECIPROCAL */
#ifdef SIGNED
return nv / (((mixeng_real)IN_MAX - IN_MIN) / 2.f);
#else
return ((mixeng_real)nv - BIAS) / BIAS;
#endif
#endif
}
static inline IN_T glue (clip_, ET) (mixeng_real v)
{
if (v >= 1.f) {
return IN_MAX;
} else if (v < -1.f) {
return IN_MIN;
}
#ifdef SIGNED
return ENDIAN_CONVERT((IN_T)(v * (((mixeng_real)IN_MAX - IN_MIN) / 2.f)));
#else
return ENDIAN_CONVERT(MIN((int64_t)(v * BIAS) + BIAS, IN_MAX));
#endif
}
#else /* !FLOAT_MIXENG */
static inline int64_t glue (conv_, ET) (IN_T v)
{
IN_T nv = ENDIAN_CONVERT (v);
#ifdef SIGNED
return ((int64_t) nv) << (32 - SHIFT);
#else
return ((int64_t) nv - BIAS) << (32 - SHIFT);
#endif
}
static inline IN_T glue (clip_, ET) (int64_t v)
{
if (v >= 0x7fffffffLL) {
return IN_MAX;
} else if (v < -2147483648LL) {
return IN_MIN;
}
#ifdef SIGNED
return ENDIAN_CONVERT ((IN_T) (v >> (32 - SHIFT)));
#else
return ENDIAN_CONVERT((IN_T)((v >> (32 - SHIFT)) + BIAS));
#endif
}
#endif
static void glue (glue (conv_, ET), _to_stereo)
(struct st_sample *dst, const void *src, int samples)
{
struct st_sample *out = dst;
IN_T *in = (IN_T *) src;
while (samples--) {
out->l = glue (conv_, ET) (*in++);
out->r = glue (conv_, ET) (*in++);
out += 1;
}
}
static void glue (glue (conv_, ET), _to_mono)
(struct st_sample *dst, const void *src, int samples)
{
struct st_sample *out = dst;
IN_T *in = (IN_T *) src;
while (samples--) {
out->l = glue (conv_, ET) (in[0]);
out->r = out->l;
out += 1;
in += 1;
}
}
static void glue (glue (clip_, ET), _from_stereo)
(void *dst, const struct st_sample *src, int samples)
{
const struct st_sample *in = src;
IN_T *out = (IN_T *) dst;
while (samples--) {
*out++ = glue (clip_, ET) (in->l);
*out++ = glue (clip_, ET) (in->r);
in += 1;
}
}
static void glue (glue (clip_, ET), _from_mono)
(void *dst, const struct st_sample *src, int samples)
{
const struct st_sample *in = src;
IN_T *out = (IN_T *) dst;
while (samples--) {
*out++ = glue (clip_, ET) (in->l + in->r);
in += 1;
}
}
#undef ET
#undef BIAS
#undef IN_T