From: Akihiko Odaki <[email protected]>
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 <[email protected]>
Acked-by: Marc-André Lureau <[email protected]>
Message-Id: <[email protected]>
---
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 5b0014bdd9a..6db742188ed 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
--
2.54.0
