[pulseaudio-discuss] [PATCH 2/2] endianmacros: Replace borked PA_FLOAT32_SWAP() with PA_READ_FLOAT32RE() / PA_WRITE_FLOAT32RE()
Peter Meerwald
pmeerw at pmeerw.net
Tue Sep 2 17:25:42 PDT 2014
From: Peter Meerwald <pmeerw at debian>
building PA with -O0 leads to test failure in mix-test on i386
issue reported by Felipe, see
http://lists.freedesktop.org/archives/pulseaudio-discuss/2014-August/021406.html
the problem is the value 0xbeffbd7f: when byte-swapped it becomes 0x7fbdffbe and according
to IEEE-754 represents a signalling NaN (starting with s111 1111 10, see http://en.wikipedia.org/wiki/NaN)
when this value is assigned to a floating point register, it becomes 0x7ffdffbe, representing
a quiet NaN (starting with s111 1111 11) -- a signalling NaN is turned into a quiet NaN!
so PA_FLOAT32_SWAP(PA_FLOAT32_SWAP(x)) != x for certain values, uhuh!
the following test code can be used; due to volatile, it will always demonstrate the issue;
without volatile, it depends on the optimization level (i386, 32-bit, gcc 4.9):
// snip
static inline float PA_FLOAT32_SWAP(float x) {
union {
float f;
uint32_t u;
} t;
t.f = x;
t.u = bswap_32(t.u);
return t.f;
}
int main() {
unsigned x = 0xbeffbd7f;
volatile float f = PA_FLOAT32_SWAP(*(float *)&x);
printf("%08x %08x %08x %f\n", 0xbeffbd7f, *(unsigned *)&f, bswap_32(*(unsigned *)&f), f);
}
// snip
the problem goes away with optimization when no temporary floating point registers are used
the proposed solution is to avoid passing swapped floating point data in a
float; this is done with new functions PA_READ_FLOAT32RE() and PA_WRITE_FLOAT32RE()
which use uint32_t to dereference a pointer and byte-swap the data, hence no temporary
float variable is used
also delete PA_FLOAT32_TO_LE()/_BE(), not used
Signed-off-by: Peter Meerwald <pmeerw at pmeerw.net>
Reported-by: Felipe Sateler <fsateler at debian.org>
---
src/pulsecore/endianmacros.h | 23 ++++++++++++-----------
src/pulsecore/mix.c | 11 ++++-------
src/pulsecore/sample-util.c | 4 ++--
src/pulsecore/sconv-s16le.c | 22 ++++++++--------------
src/pulsecore/svolume_c.c | 4 ++--
src/tests/mix-test.c | 4 ++--
src/tests/resampler-test.c | 4 ++--
7 files changed, 32 insertions(+), 40 deletions(-)
diff --git a/src/pulsecore/endianmacros.h b/src/pulsecore/endianmacros.h
index 4822fc4..2e73136 100644
--- a/src/pulsecore/endianmacros.h
+++ b/src/pulsecore/endianmacros.h
@@ -71,25 +71,32 @@ static inline void PA_WRITE24LE(uint8_t *p, uint32_t u) {
p[0] = (uint8_t) u;
}
-static inline float PA_FLOAT32_SWAP(float x) {
+static inline float PA_READ_FLOAT32RE(const void *p) {
union {
float f;
uint32_t u;
} t;
- t.f = x;
- t.u = PA_UINT32_SWAP(t.u);
+ t.u = PA_UINT32_SWAP(*(uint32_t *) p);
return t.f;
}
+static inline void PA_WRITE_FLOAT32RE(void *p, float x) {
+ union {
+ float f;
+ uint32_t u;
+ } t;
+
+ t.f = x;
+ *(uint32_t *) p = PA_UINT32_SWAP(t.u);
+}
+
#define PA_MAYBE_INT16_SWAP(c,x) ((c) ? PA_INT16_SWAP(x) : (x))
#define PA_MAYBE_UINT16_SWAP(c,x) ((c) ? PA_UINT16_SWAP(x) : (x))
#define PA_MAYBE_INT32_SWAP(c,x) ((c) ? PA_INT32_SWAP(x) : (x))
#define PA_MAYBE_UINT32_SWAP(c,x) ((c) ? PA_UINT32_SWAP(x) : (x))
-#define PA_MAYBE_FLOAT32_SWAP(c,x) ((c) ? PA_FLOAT32_SWAP(x) : (x))
-
#ifdef WORDS_BIGENDIAN
#define PA_INT16_FROM_LE(x) PA_INT16_SWAP(x)
#define PA_INT16_FROM_BE(x) ((int16_t)(x))
@@ -115,9 +122,6 @@ static inline float PA_FLOAT32_SWAP(float x) {
#define PA_UINT32_TO_LE(x) PA_UINT32_SWAP(x)
#define PA_UINT32_TO_BE(x) ((uint32_t)(x))
- #define PA_FLOAT32_TO_LE(x) PA_FLOAT32_SWAP(x)
- #define PA_FLOAT32_TO_BE(x) ((float) (x))
-
#define PA_READ24NE(x) PA_READ24BE(x)
#define PA_WRITE24NE(x,y) PA_WRITE24BE((x),(y))
@@ -148,9 +152,6 @@ static inline float PA_FLOAT32_SWAP(float x) {
#define PA_UINT32_TO_LE(x) ((uint32_t)(x))
#define PA_UINT32_TO_BE(x) PA_UINT32_SWAP(x)
- #define PA_FLOAT32_TO_LE(x) ((float) (x))
- #define PA_FLOAT32_TO_BE(x) PA_FLOAT32_SWAP(x)
-
#define PA_READ24NE(x) PA_READ24LE(x)
#define PA_WRITE24NE(x,y) PA_WRITE24LE((x),(y))
diff --git a/src/pulsecore/mix.c b/src/pulsecore/mix.c
index 10567d6..03c71f0 100644
--- a/src/pulsecore/mix.c
+++ b/src/pulsecore/mix.c
@@ -576,17 +576,14 @@ static void pa_mix_float32re_c(pa_mix_info streams[], unsigned nstreams, unsigne
for (i = 0; i < nstreams; i++) {
pa_mix_info *m = streams + i;
- float v, cv = m->linear[channel].f;
+ float cv = m->linear[channel].f;
- if (PA_LIKELY(cv > 0)) {
- v = PA_FLOAT32_SWAP(*(float*) m->ptr);
- v *= cv;
- sum += v;
- }
+ if (PA_LIKELY(cv > 0))
+ sum += PA_READ_FLOAT32RE(m->ptr) * cv;
m->ptr = (uint8_t*) m->ptr + sizeof(float);
}
- *data = PA_FLOAT32_SWAP(sum);
+ PA_WRITE_FLOAT32RE(data, sum);
if (PA_UNLIKELY(++channel >= channels))
channel = 0;
diff --git a/src/pulsecore/sample-util.c b/src/pulsecore/sample-util.c
index dc5c1fd..539f3b8 100644
--- a/src/pulsecore/sample-util.c
+++ b/src/pulsecore/sample-util.c
@@ -296,9 +296,9 @@ void pa_sample_clamp(pa_sample_format_t format, void *dst, size_t dstr, const vo
for (; n > 0; n--) {
float f;
- f = PA_FLOAT32_SWAP(*s);
+ f = PA_READ_FLOAT32RE(s);
f = PA_CLAMP_UNLIKELY(f, -1.0f, 1.0f);
- *d = PA_FLOAT32_SWAP(f);
+ PA_WRITE_FLOAT32RE(d, f);
s = (const float*) ((const uint8_t*) s + sstr);
d = (float*) ((uint8_t*) d + dstr);
diff --git a/src/pulsecore/sconv-s16le.c b/src/pulsecore/sconv-s16le.c
index 45cf972..0c1d16c 100644
--- a/src/pulsecore/sconv-s16le.c
+++ b/src/pulsecore/sconv-s16le.c
@@ -157,8 +157,7 @@ void pa_sconv_s16le_to_float32re(unsigned n, const int16_t *a, float *b) {
for (; n > 0; n--) {
int16_t s = *(a++);
float k = INT16_FROM(s) * (1.0f / (1 << 15));
- k = PA_FLOAT32_SWAP(k);
- *(b++) = k;
+ PA_WRITE_FLOAT32RE(b++, k);
}
}
@@ -169,8 +168,7 @@ void pa_sconv_s32le_to_float32re(unsigned n, const int32_t *a, float *b) {
for (; n > 0; n--) {
int32_t s = *(a++);
float k = INT32_FROM(s) * (1.0f / (1U << 31));
- k = PA_FLOAT32_SWAP(k);
- *(b++) = k;
+ PA_WRITE_FLOAT32RE(b++, k);
}
}
@@ -180,8 +178,7 @@ void pa_sconv_s16le_from_float32re(unsigned n, const float *a, int16_t *b) {
for (; n > 0; n--) {
int16_t s;
- float v = *(a++);
- v = PA_FLOAT32_SWAP(v) * (1 << 15);
+ float v = PA_READ_FLOAT32RE(a++) * (1 << 15);
s = (int16_t) PA_CLAMP_UNLIKELY(lrintf(v), -0x8000, 0x7FFF);
*(b++) = INT16_TO(s);
}
@@ -193,8 +190,7 @@ void pa_sconv_s32le_from_float32re(unsigned n, const float *a, int32_t *b) {
for (; n > 0; n--) {
int32_t s;
- float v = *(a++);
- v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ float v = PA_READ_FLOAT32RE(a++) * (1U << 31);
s = (int32_t) PA_CLAMP_UNLIKELY(llrintf(v), -0x80000000LL, 0x7FFFFFFFLL);
*(b++) = INT32_TO(s);
}
@@ -325,7 +321,7 @@ void pa_sconv_s24le_to_float32re(unsigned n, const uint8_t *a, float *b) {
for (; n > 0; n--) {
int32_t s = READ24(a) << 8;
float k = s * (1.0f / (1U << 31));
- *b = PA_FLOAT32_SWAP(k);
+ PA_WRITE_FLOAT32RE(b, k);
a += 3;
b++;
}
@@ -337,8 +333,7 @@ void pa_sconv_s24le_from_float32re(unsigned n, const float *a, uint8_t *b) {
for (; n > 0; n--) {
int32_t s;
- float v = *a;
- v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ float v = PA_READ_FLOAT32RE(a) * (1U << 31);
s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
WRITE24(b, ((uint32_t) s) >> 8);
a++;
@@ -411,7 +406,7 @@ void pa_sconv_s24_32le_to_float32re(unsigned n, const uint32_t *a, float *b) {
for (; n > 0; n--) {
int32_t s = (int32_t) (UINT32_FROM(*a) << 8);
float k = s * (1.0f / (1U << 31));
- *b = PA_FLOAT32_SWAP(k);
+ PA_WRITE_FLOAT32RE(b, k);
a++;
b++;
}
@@ -437,8 +432,7 @@ void pa_sconv_s24_32le_from_float32re(unsigned n, const float *a, uint32_t *b) {
for (; n > 0; n--) {
int32_t s;
- float v = *a;
- v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ float v = PA_READ_FLOAT32RE(a) * (1U << 31);
s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
*b = UINT32_TO(((uint32_t) s) >> 8);
a++;
diff --git a/src/pulsecore/svolume_c.c b/src/pulsecore/svolume_c.c
index ad2df18..2e2db12 100644
--- a/src/pulsecore/svolume_c.c
+++ b/src/pulsecore/svolume_c.c
@@ -125,9 +125,9 @@ static void pa_volume_float32re_c(float *samples, const float *volumes, unsigned
for (channel = 0; length; length--) {
float t;
- t = PA_FLOAT32_SWAP(*samples);
+ t = PA_READ_FLOAT32RE(samples);
t *= volumes[channel];
- *samples++ = PA_FLOAT32_SWAP(t);
+ PA_WRITE_FLOAT32RE(samples++, t);
if (PA_UNLIKELY(++channel >= channels))
channel = 0;
diff --git a/src/tests/mix-test.c b/src/tests/mix-test.c
index d5bae13..e95607d 100644
--- a/src/tests/mix-test.c
+++ b/src/tests/mix-test.c
@@ -150,7 +150,7 @@ static void compare_block(const pa_sample_spec *ss, const pa_memchunk *chunk, in
float *u = d;
for (i = 0; i < chunk->length / pa_frame_size(ss); i++) {
- float uu = PA_MAYBE_FLOAT32_SWAP(ss->format != PA_SAMPLE_FLOAT32NE, *u);
+ float uu = ss->format == PA_SAMPLE_FLOAT32NE ? *u : PA_READ_FLOAT32RE(u);
fail_unless(fabsf(uu - *v) <= 1e-6f, NULL);
++u;
++v;
@@ -264,7 +264,7 @@ static pa_memblock* generate_block(pa_mempool *pool, const pa_sample_spec *ss) {
if (ss->format == PA_SAMPLE_FLOAT32RE) {
float *u = d;
for (i = 0; i < 10; i++)
- u[i] = PA_FLOAT32_SWAP(float32ne_result[0][i]);
+ PA_WRITE_FLOAT32RE(&u[i], float32ne_result[0][i]);
} else
memcpy(d, float32ne_result[0], sizeof(float32ne_result[0]));
diff --git a/src/tests/resampler-test.c b/src/tests/resampler-test.c
index 60345af..f547770 100644
--- a/src/tests/resampler-test.c
+++ b/src/tests/resampler-test.c
@@ -98,7 +98,7 @@ static void dump_block(const char *label, const pa_sample_spec *ss, const pa_mem
float *u = d;
for (i = 0; i < chunk->length / pa_frame_size(ss); i++) {
- printf("%4.3g ", ss->format == PA_SAMPLE_FLOAT32NE ? *u : PA_FLOAT32_SWAP(*u));
+ printf("%4.3g ", ss->format == PA_SAMPLE_FLOAT32NE ? *u : PA_READ_FLOAT32RE(u));
u++;
}
@@ -222,7 +222,7 @@ static pa_memblock* generate_block(pa_mempool *pool, const pa_sample_spec *ss) {
if (ss->format == PA_SAMPLE_FLOAT32RE)
for (i = 0; i < 10; i++)
- u[i] = PA_FLOAT32_SWAP(u[i]);
+ PA_WRITE_FLOAT32RE(&u[i], u[i]);
break;
}
--
1.9.1
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