From 64abf45516f884c344a894cebebe06d861b16b2a Mon Sep 17 00:00:00 2001 From: Akihiko Odaki Date: Thu, 23 Apr 2026 22:55:23 +0900 Subject: [PATCH] audio: Use unsigned PCM bias MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Marc-André Lureau Message-Id: <20260423-audio-v1-3-e1d6b65c76f9@rsg.ci.i.u-tokyo.ac.jp> --- audio/mixeng_template.h | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/audio/mixeng_template.h b/audio/mixeng_template.h index 5b0014bdd9..6db742188e 100644 --- a/audio/mixeng_template.h +++ b/audio/mixeng_template.h @@ -28,7 +28,7 @@ */ #ifndef SIGNED -#define HALF (IN_MAX >> 1) +#define BIAS ((IN_T)1 << (SHIFT - 1)) #endif #define ET glue (ENDIAN_CONVERSION, glue (glue (glue (_, ITYPE), BSIZE), _t)) @@ -43,13 +43,13 @@ static inline mixeng_real glue (conv_, ET) (IN_T v) #ifdef SIGNED return nv * (2.f / ((mixeng_real)IN_MAX - IN_MIN)); #else - return ((mixeng_real)nv - HALF) * (2.f / (mixeng_real)IN_MAX); + 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 - HALF) / ((mixeng_real)IN_MAX / 2.f); + return ((mixeng_real)nv - BIAS) / BIAS; #endif #endif } @@ -65,9 +65,7 @@ static inline IN_T glue (clip_, ET) (mixeng_real v) #ifdef SIGNED return ENDIAN_CONVERT((IN_T)(v * (((mixeng_real)IN_MAX - IN_MIN) / 2.f))); #else - return ENDIAN_CONVERT(MIN((int64_t)((v * ((mixeng_real)IN_MAX / 2.f)) + - HALF), - IN_MAX)); + return ENDIAN_CONVERT(MIN((int64_t)(v * BIAS) + BIAS, IN_MAX)); #endif } @@ -79,7 +77,7 @@ static inline int64_t glue (conv_, ET) (IN_T v) #ifdef SIGNED return ((int64_t) nv) << (32 - SHIFT); #else - return ((int64_t) nv - HALF) << (32 - SHIFT); + return ((int64_t) nv - BIAS) << (32 - SHIFT); #endif } @@ -94,7 +92,7 @@ static inline IN_T glue (clip_, ET) (int64_t v) #ifdef SIGNED return ENDIAN_CONVERT ((IN_T) (v >> (32 - SHIFT))); #else - return ENDIAN_CONVERT ((IN_T) ((v >> (32 - SHIFT)) + HALF)); + return ENDIAN_CONVERT((IN_T)((v >> (32 - SHIFT)) + BIAS)); #endif } #endif @@ -150,5 +148,5 @@ static void glue (glue (clip_, ET), _from_mono) } #undef ET -#undef HALF +#undef BIAS #undef IN_T