From: Peter Meerwald <p.meerwald@xxxxxxxxxxxxxxxxxx>
use (1<<15) instead of 0x7fff as a factor when converting from s16 to float32
use (1<<31) instead of 0x7fffffff as a factor when converting from s32 to float32
the change is motivated by the following desireable properties:
* s16_from_f32(f32_from_s16(x)) == x for all possible s16 values
* x / (1.0f << 15) == x * (1.0f / (1 << 15)) for all x in s16
above changes enable easier optimization while guaranteeing bit-exact results
further, other audio sample conversion code (libavresample) does it the same way
v3 (comments Tanu):
* fix saturation in pa_sconv_s16le_from_f32ne_neon(), use vqrshrn
v2 (comments Tanu):
* fix comments in ARM NEON code
* use llrintf() in pa_sconv_s32le_from_float32ne()
Signed-off-by: Peter Meerwald <p.meerwald at bct-electronic.com>
Cc: Tanu Kaskinen <tanuk at iki.fi>
---
src/pulsecore/sconv-s16le.c | 84 ++++++++++++++++++++-------------------------
src/pulsecore/sconv_neon.c | 25 ++++++--------
src/pulsecore/sconv_sse.c | 66 +++++++++++++++++------------------
3 files changed, 79 insertions(+), 96 deletions(-)
diff --git a/src/pulsecore/sconv-s16le.c b/src/pulsecore/sconv-s16le.c
index 138e418..45cf972 100644
--- a/src/pulsecore/sconv-s16le.c
+++ b/src/pulsecore/sconv-s16le.c
@@ -85,11 +85,11 @@ void pa_sconv_s16le_to_float32ne(unsigned n, const int16_t *a, float *b) {
#if SWAP_WORDS == 1
for (; n > 0; n--) {
int16_t s = *(a++);
- *(b++) = ((float) INT16_FROM(s))/(float) 0x7FFF;
+ *(b++) = INT16_FROM(s) * (1.0f / (1 << 15));
}
#else
for (; n > 0; n--)
- *(b++) = ((float) (*(a++)))/(float) 0x7FFF;
+ *(b++) = *(a++) * (1.0f / (1 << 15));
#endif
}
@@ -100,11 +100,11 @@ void pa_sconv_s32le_to_float32ne(unsigned n, const int32_t *a, float *b) {
#if SWAP_WORDS == 1
for (; n > 0; n--) {
int32_t s = *(a++);
- *(b++) = (float) (((double) INT32_FROM(s))/0x7FFFFFFF);
+ *(b++) = INT32_FROM(s) * (1.0f / (1U << 31));
}
#else
for (; n > 0; n--)
- *(b++) = (float) (((double) (*(a++)))/0x7FFFFFFF);
+ *(b++) = *(a++) * (1.0f / (1U << 31));
#endif
}
@@ -115,18 +115,16 @@ void pa_sconv_s16le_from_float32ne(unsigned n, const float *a, int16_t *b) {
#if SWAP_WORDS == 1
for (; n > 0; n--) {
int16_t s;
- float v = *(a++);
+ float v = *(a++) * (1 << 15);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.f);
- s = (int16_t) lrintf(v * 0x7FFF);
+ s = (int16_t) PA_CLAMP_UNLIKELY(lrintf(v), -0x8000, 0x7FFF);
*(b++) = INT16_TO(s);
}
#else
for (; n > 0; n--) {
- float v = *(a++);
+ float v = *(a++) * (1 << 15);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.f);
- *(b++) = (int16_t) lrintf(v * 0x7FFF);
+ *(b++) = (int16_t) PA_CLAMP_UNLIKELY(lrintf(v), -0x8000, 0x7FFF);
}
#endif
}
@@ -138,18 +136,16 @@ void pa_sconv_s32le_from_float32ne(unsigned n, const float *a, int32_t *b) {
#if SWAP_WORDS == 1
for (; n > 0; n--) {
int32_t s;
- float v = *(a++);
+ float v = *(a++) * (1U << 31);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrintf(v), -0x80000000LL, 0x7FFFFFFFLL);
*(b++) = INT32_TO(s);
}
#else
for (; n > 0; n--) {
- float v = *(a++);
+ float v = *(a++) * (1U << 31);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- *(b++) = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ *(b++) = (int32_t) PA_CLAMP_UNLIKELY(llrintf(v), -0x80000000LL, 0x7FFFFFFFLL);
}
#endif
}
@@ -160,7 +156,7 @@ void pa_sconv_s16le_to_float32re(unsigned n, const int16_t *a, float *b) {
for (; n > 0; n--) {
int16_t s = *(a++);
- float k = ((float) INT16_FROM(s))/0x7FFF;
+ float k = INT16_FROM(s) * (1.0f / (1 << 15));
k = PA_FLOAT32_SWAP(k);
*(b++) = k;
}
@@ -172,7 +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 = (float) (((double) INT32_FROM(s))/0x7FFFFFFF);
+ float k = INT32_FROM(s) * (1.0f / (1U << 31));
k = PA_FLOAT32_SWAP(k);
*(b++) = k;
}
@@ -185,9 +181,8 @@ 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);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int16_t) lrintf(v * 0x7FFF);
+ v = PA_FLOAT32_SWAP(v) * (1 << 15);
+ s = (int16_t) PA_CLAMP_UNLIKELY(lrintf(v), -0x8000, 0x7FFF);
*(b++) = INT16_TO(s);
}
}
@@ -199,9 +194,8 @@ 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);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * 0x7FFFFFFF);
+ v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrintf(v), -0x80000000LL, 0x7FFFFFFFLL);
*(b++) = INT32_TO(s);
}
}
@@ -304,9 +298,9 @@ void pa_sconv_s24le_to_float32ne(unsigned n, const uint8_t *a, float *b) {
for (; n > 0; n--) {
int32_t s = READ24(a) << 8;
- *b = ((float) s) / 0x7FFFFFFF;
+ *b = s * (1.0f / (1U << 31));
a += 3;
- b ++;
+ b++;
}
}
@@ -316,12 +310,11 @@ void pa_sconv_s24le_from_float32ne(unsigned n, const float *a, uint8_t *b) {
for (; n > 0; n--) {
int32_t s;
- float v = *a;
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ float v = *a * (1U << 31);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
WRITE24(b, ((uint32_t) s) >> 8);
a++;
- b+=3;
+ b += 3;
}
}
@@ -331,10 +324,10 @@ 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 = ((float) s) / 0x7FFFFFFF;
+ float k = s * (1.0f / (1U << 31));
*b = PA_FLOAT32_SWAP(k);
a += 3;
- b ++;
+ b++;
}
}
@@ -345,9 +338,8 @@ 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);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
WRITE24(b, ((uint32_t) s) >> 8);
a++;
b+=3;
@@ -406,9 +398,9 @@ void pa_sconv_s24_32le_to_float32ne(unsigned n, const uint32_t *a, float *b) {
for (; n > 0; n--) {
int32_t s = (int32_t) (UINT32_FROM(*a) << 8);
- *b = (float) s / (float) 0x7FFFFFFF;
- a ++;
- b ++;
+ *b = s * (1.0f / (1U << 31));
+ a++;
+ b++;
}
}
@@ -418,10 +410,10 @@ 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 = (float) s / (float) 0x7FFFFFFF;
+ float k = s * (1.0f / (1U << 31));
*b = PA_FLOAT32_SWAP(k);
- a ++;
- b ++;
+ a++;
+ b++;
}
}
@@ -431,9 +423,8 @@ void pa_sconv_s24_32le_from_float32ne(unsigned n, const float *a, uint32_t *b) {
for (; n > 0; n--) {
int32_t s;
- float v = *a;
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ float v = *a * (1U << 31);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
*b = UINT32_TO(((uint32_t) s) >> 8);
a++;
b++;
@@ -447,9 +438,8 @@ 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);
- v = PA_CLAMP_UNLIKELY(v, -1.0f, 1.0f);
- s = (int32_t) lrint((double) v * (double) 0x7FFFFFFF);
+ v = PA_FLOAT32_SWAP(v) * (1U << 31);
+ s = (int32_t) PA_CLAMP_UNLIKELY(llrint(v), -0x80000000LL, 0x7FFFFFFFLL);
*b = UINT32_TO(((uint32_t) s) >> 8);
a++;
b++;
diff --git a/src/pulsecore/sconv_neon.c b/src/pulsecore/sconv_neon.c
index 6fd966d..ddcdcc2 100644
--- a/src/pulsecore/sconv_neon.c
+++ b/src/pulsecore/sconv_neon.c
@@ -36,18 +36,13 @@ static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t
"movs %[n], %[n], lsr #2 \n\t"
"beq 2f \n\t"
- "vdup.f32 q2, %[plusone] \n\t"
- "vneg.f32 q3, q2 \n\t"
- "vdup.f32 q4, %[scale] \n\t"
- "vdup.u32 q5, %[mask] \n\t"
+ "vdup.f32 q1, %[scale] \n\t"
"1: \n\t"
"vld1.32 {q0}, [%[src]]! \n\t"
- "vmin.f32 q0, q0, q2 \n\t" /* clamp */
- "vmax.f32 q0, q0, q3 \n\t"
- "vmul.f32 q0, q0, q4 \n\t" /* scale */
- "vcvt.s32.f32 q0, q0, #16 \n\t" /* narrow */
- "vrshrn.s32 d0, q0, #16 \n\t"
+ "vmul.f32 q0, q0, q1 \n\t" /* scale */
+ "vcvt.s32.f32 q0, q0, #16 \n\t" /* s32<-f32 as 16:16 fixed-point */
+ "vqrshrn.s32 d0, q0, #16 \n\t" /* shift, round, narrow */
"subs %[n], %[n], #1 \n\t"
"vst1.16 {d0}, [%[dst]]! \n\t"
"bgt 1b \n\t"
@@ -55,13 +50,13 @@ static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t
"2: \n\t"
: [dst] "+r" (dst), [src] "+r" (src), [n] "+r" (n) /* output operands (or input operands that get modified) */
- : [plusone] "r" (1.0f), [scale] "r" (32767.0f), [mask] "r" (0x80000000) /* input operands */
- : "memory", "cc", "q0", "q1", "q2", "q3", "q4", "q5", "q6" /* clobber list */
+ : [scale] "r" (32768.0f) /* input operands */
+ : "memory", "cc", "q0", "q1" /* clobber list */
);
/* leftovers */
while (i--) {
- *dst++ = (int16_t) lrintf(PA_CLAMP_UNLIKELY(*src, -1.0f, 1.0f) * 0x7FFF);
+ *dst++ = (int16_t) PA_CLAMP_UNLIKELY(lrintf(*src * (1 << 15)), -0x8000, 0x7FFF);
src++;
}
}
@@ -69,7 +64,7 @@ static void pa_sconv_s16le_from_f32ne_neon(unsigned n, const float *src, int16_t
static void pa_sconv_s16le_to_f32ne_neon(unsigned n, const int16_t *src, float *dst) {
unsigned i = n & 3;
- const float invscale = 1.0f / 0x7FFF;
+ const float invscale = 1.0f / (1 << 15);
__asm__ __volatile__ (
"movs %[n], %[n], lsr #2 \n\t"
@@ -79,8 +74,8 @@ static void pa_sconv_s16le_to_f32ne_neon(unsigned n, const int16_t *src, float *
"1: \n\t"
"vld1.16 {d0}, [%[src]]! \n\t"
- "vmovl.s16 q0, d0 \n\t"
- "vcvt.f32.s32 q0, q0 \n\t"
+ "vmovl.s16 q0, d0 \n\t" /* widen */
+ "vcvt.f32.s32 q0, q0 \n\t" /* f32<-s32 */
"vmul.f32 q0, q0, q1 \n\t"
"subs %[n], %[n], #1 \n\t"
"vst1.32 {q0}, [%[dst]]! \n\t"
diff --git a/src/pulsecore/sconv_sse.c b/src/pulsecore/sconv_sse.c
index 34b59fa..2f84f5a 100644
--- a/src/pulsecore/sconv_sse.c
+++ b/src/pulsecore/sconv_sse.c
@@ -35,17 +35,13 @@
#if !defined(__APPLE__) && defined (__i386__) || defined (__amd64__)
-static const PA_DECLARE_ALIGNED (16, float, one[4]) = { 1.0, 1.0, 1.0, 1.0 };
-static const PA_DECLARE_ALIGNED (16, float, mone[4]) = { -1.0, -1.0, -1.0, -1.0 };
-static const PA_DECLARE_ALIGNED (16, float, scale[4]) = { 0x7fff, 0x7fff, 0x7fff, 0x7fff };
+static const PA_DECLARE_ALIGNED (16, float, scale[4]) = { 0x8000, 0x8000, 0x8000, 0x8000 };
static void pa_sconv_s16le_from_f32ne_sse(unsigned n, const float *a, int16_t *b) {
pa_reg_x86 temp, i;
__asm__ __volatile__ (
" movaps %5, %%xmm5 \n\t"
- " movaps %6, %%xmm6 \n\t"
- " movaps %7, %%xmm7 \n\t"
" xor %0, %0 \n\t"
" mov %4, %1 \n\t"
@@ -56,12 +52,8 @@ static void pa_sconv_s16le_from_f32ne_sse(unsigned n, const float *a, int16_t *b
"1: \n\t"
" movups (%q2, %0, 2), %%xmm0 \n\t" /* read 8 floats */
" movups 16(%q2, %0, 2), %%xmm2 \n\t"
- " minps %%xmm5, %%xmm0 \n\t" /* clamp to 1.0 */
- " minps %%xmm5, %%xmm2 \n\t"
- " maxps %%xmm6, %%xmm0 \n\t" /* clamp to -1.0 */
- " maxps %%xmm6, %%xmm2 \n\t"
- " mulps %%xmm7, %%xmm0 \n\t" /* *= 0x7fff */
- " mulps %%xmm7, %%xmm2 \n\t"
+ " mulps %%xmm5, %%xmm0 \n\t" /* *= 0x8000 */
+ " mulps %%xmm5, %%xmm2 \n\t"
" cvtps2pi %%xmm0, %%mm0 \n\t" /* low part to int */
" cvtps2pi %%xmm2, %%mm2 \n\t"
@@ -73,7 +65,7 @@ static void pa_sconv_s16le_from_f32ne_sse(unsigned n, const float *a, int16_t *b
" packssdw %%mm1, %%mm0 \n\t" /* pack parts */
" packssdw %%mm3, %%mm2 \n\t"
" movq %%mm0, (%q3, %0) \n\t"
- " movq %%mm2, 8(%q3, %0) \n\t"
+ " movq %%mm2, 8(%q3, %0) \n\t"
" add $16, %0 \n\t"
" dec %1 \n\t"
@@ -82,24 +74,30 @@ static void pa_sconv_s16le_from_f32ne_sse(unsigned n, const float *a, int16_t *b
"2: \n\t"
" mov %4, %1 \n\t" /* prepare for leftovers */
" and $7, %1 \n\t"
- " je 4f \n\t"
+ " je 5f \n\t"
"3: \n\t"
" movss (%q2, %0, 2), %%xmm0 \n\t"
- " minss %%xmm5, %%xmm0 \n\t"
- " maxss %%xmm6, %%xmm0 \n\t"
- " mulss %%xmm7, %%xmm0 \n\t"
+ " mulss %%xmm5, %%xmm0 \n\t"
+ " cvtss2si %%xmm0, %4 \n\t"
+ " add $0x8000, %4 \n\t" /* check for saturation */
+ " and $~0xffff, %4 \n\t"
" cvtss2si %%xmm0, %4 \n\t"
- " movw %w4, (%q3, %0) \n\t"
+ " je 4f \n\t"
+ " sar $31, %4 \n\t"
+ " xor $0x7fff, %4 \n\t"
+
+ "4: \n\t"
+ " movw %w4, (%q3, %0) \n\t" /* store leftover */
" add $2, %0 \n\t"
" dec %1 \n\t"
" jne 3b \n\t"
- "4: \n\t"
+ "5: \n\t"
" emms \n\t"
: "=&r" (i), "=&r" (temp)
- : "r" (a), "r" (b), "r" ((pa_reg_x86)n), "m" (*one), "m" (*mone), "m" (*scale)
+ : "r" (a), "r" (b), "r" ((pa_reg_x86)n), "m" (*scale)
: "cc", "memory"
);
}
@@ -109,8 +107,6 @@ static void pa_sconv_s16le_from_f32ne_sse2(unsigned n, const float *a, int16_t *
__asm__ __volatile__ (
" movaps %5, %%xmm5 \n\t"
- " movaps %6, %%xmm6 \n\t"
- " movaps %7, %%xmm7 \n\t"
" xor %0, %0 \n\t"
" mov %4, %1 \n\t"
@@ -121,12 +117,8 @@ static void pa_sconv_s16le_from_f32ne_sse2(unsigned n, const float *a, int16_t *
"1: \n\t"
" movups (%q2, %0, 2), %%xmm0 \n\t" /* read 8 floats */
" movups 16(%q2, %0, 2), %%xmm2 \n\t"
- " minps %%xmm5, %%xmm0 \n\t" /* clamp to 1.0 */
- " minps %%xmm5, %%xmm2 \n\t"
- " maxps %%xmm6, %%xmm0 \n\t" /* clamp to -1.0 */
- " maxps %%xmm6, %%xmm2 \n\t"
- " mulps %%xmm7, %%xmm0 \n\t" /* *= 0x7fff */
- " mulps %%xmm7, %%xmm2 \n\t"
+ " mulps %%xmm5, %%xmm0 \n\t" /* *= 0x8000 */
+ " mulps %%xmm5, %%xmm2 \n\t"
" cvtps2dq %%xmm0, %%xmm0 \n\t"
" cvtps2dq %%xmm2, %%xmm2 \n\t"
@@ -141,23 +133,29 @@ static void pa_sconv_s16le_from_f32ne_sse2(unsigned n, const float *a, int16_t *
"2: \n\t"
" mov %4, %1 \n\t" /* prepare for leftovers */
" and $7, %1 \n\t"
- " je 4f \n\t"
+ " je 5f \n\t"
"3: \n\t"
" movss (%q2, %0, 2), %%xmm0 \n\t"
- " minss %%xmm5, %%xmm0 \n\t"
- " maxss %%xmm6, %%xmm0 \n\t"
- " mulss %%xmm7, %%xmm0 \n\t"
+ " mulss %%xmm5, %%xmm0 \n\t"
+ " cvtss2si %%xmm0, %4 \n\t"
+ " add $0x8000, %4 \n\t"
+ " and $~0xffff, %4 \n\t" /* check for saturation */
" cvtss2si %%xmm0, %4 \n\t"
- " movw %w4, (%q3, %0) \n\t"
+ " je 4f \n\t"
+ " sar $31, %4 \n\t"
+ " xor $0x7fff, %4 \n\t"
+
+ "4: \n\t"
+ " movw %w4, (%q3, %0) \n\t" /* store leftover */
" add $2, %0 \n\t"
" dec %1 \n\t"
" jne 3b \n\t"
- "4: \n\t"
+ "5: \n\t"
: "=&r" (i), "=&r" (temp)
- : "r" (a), "r" (b), "r" ((pa_reg_x86)n), "m" (*one), "m" (*mone), "m" (*scale)
+ : "r" (a), "r" (b), "r" ((pa_reg_x86)n), "m" (*scale)
: "cc", "memory"
);
}
--
1.8.1.1
