mirror of
https://gitlab.com/qemu-project/qemu.git
synced 2026-05-06 12:27:32 -04:00
Akihiko Odaki
64abf45516
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>