GitHub/dsd-fme
1
0
Fork 0
mirror of https://github.com/lwvmobile/dsd-fme.git synced 2026-11-13 01:07:24 -05:00
Code Issues Packages Projects Releases Wiki Activity

rtl_sdr_fm: fix rotate+widen tail handling (scalar/AVX2/NEON) to preserve 90° rotation and add SSSE3 rotate+widen with runtime dispatch on x86. Also include tmmintrin and clarify SSE2 fallback comment.

Browse Source
This commit is contained in:
arancormonk
2025-09-03 23:33:32 -04:00
parent 2ce089ccf8
commit 5834127ff7
1 changed files with 68 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
src/rtl_sdr_fm.cpp
View File

@@ -36,6 +36,7 @@
#if defined(__x86_64__) || defined(__i386__)
#include <immintrin.h>
#include <emmintrin.h>
#include <tmmintrin.h>
#endif
#if defined(__ARM_NEON) || defined(__ARM_NEON__) || defined(__aarch64__)
#include <arm_neon.h>
@@ -174,9 +175,28 @@ static inline void widen_rotate90_u8_to_s16_bias127_scalar(const unsigned char *
dst[i + 6] = q3;
dst[i + 7] = (int16_t)(1 - i3);
}
for (; i + 1 < len; i += 2) {
dst[i + 0] = (int16_t)src[i + 0] - 127;
dst[i + 1] = (int16_t)src[i + 1] - 127;
/* Tail: apply rotation pattern for remaining up to 6 samples */
if (i < len) {
uint32_t base = i;
uint32_t rem = len - base;
if (rem >= 2) {
int16_t i0 = (int16_t)src[base + 0] - 127;
int16_t q0 = (int16_t)src[base + 1] - 127;
dst[base + 0] = i0;
dst[base + 1] = q0;
}
if (rem >= 4) {
int16_t i1 = (int16_t)src[base + 2] - 127;
int16_t q1 = (int16_t)src[base + 3] - 127;
dst[base + 2] = (int16_t)(1 - q1);
dst[base + 3] = i1;
}
if (rem >= 6) {
int16_t i2 = (int16_t)src[base + 4] - 127;
int16_t q2 = (int16_t)src[base + 5] - 127;
dst[base + 4] = (int16_t)(1 - i2);
dst[base + 5] = (int16_t)(1 - q2);
}
}
}
@@ -235,9 +255,9 @@ static void DSD_FME_TARGET_ATTR("avx2") widen_rotate90_u8_to_s16_bias127_avx2(co
_mm256_storeu_si256((__m256i*)(dst + i), out_lo);
_mm256_storeu_si256((__m256i*)(dst + i + 16), out_hi);
}
for (; i + 1 < len; i += 2) {
dst[i + 0] = (int16_t)src[i + 0] - 127;
dst[i + 1] = (int16_t)src[i + 1] - 127;
/* Tail: preserve rotation via scalar helper */
if (i < len) {
widen_rotate90_u8_to_s16_bias127_scalar(src + i, dst + i, len - i);
}
}
@@ -261,11 +281,43 @@ static void DSD_FME_TARGET_ATTR("sse2") widen_u8_to_s16_bias127_sse2(const unsig
static void DSD_FME_TARGET_ATTR("sse2") widen_rotate90_u8_to_s16_bias127_sse2(const unsigned char *src, int16_t *dst, uint32_t len)
{
/* Keep scalar logic for correctness without SSSE3 pshufb */
/* Keep scalar logic for correctness without SSSE3 pshufb (SSE2 lacks byte shuffle). */
widen_rotate90_u8_to_s16_bias127_scalar(src, dst, len);
}
#endif /* x86 */
#if defined(__x86_64__) || defined(__i386__)
/* SSSE3 specialization (rotate+widen) */
static void DSD_FME_TARGET_ATTR("ssse3") widen_rotate90_u8_to_s16_bias127_ssse3(const unsigned char *src, int16_t *dst, uint32_t len)
{
uint32_t i = 0;
const __m128i shuffle = _mm_setr_epi8(
0, 1, 3, 2, 4, 5, 7, 6, 8, 9,11,10,12,13,15,14);
const __m128i mask_sel = _mm_setr_epi16(
0x0000,0x0000,0xFFFF,0x0000,0xFFFF,0xFFFF,0x0000,0xFFFF);
const __m128i c127 = _mm_set1_epi16(127);
const __m128i c128 = _mm_set1_epi16(128);
const __m128i zero = _mm_setzero_si128();
for (; i + 16 <= len; i += 16) {
__m128i v8 = _mm_loadu_si128((const __m128i*)(src + i));
__m128i sh = _mm_shuffle_epi8(v8, shuffle);
__m128i v16_lo = _mm_unpacklo_epi8(sh, zero);
__m128i v16_hi = _mm_unpackhi_epi8(sh, zero);
__m128i bs_lo = _mm_sub_epi16(v16_lo, c127);
__m128i bm_lo = _mm_sub_epi16(c128, v16_lo);
__m128i bs_hi = _mm_sub_epi16(v16_hi, c127);
__m128i bm_hi = _mm_sub_epi16(c128, v16_hi);
__m128i out_lo = _mm_or_si128(_mm_and_si128(bm_lo, mask_sel), _mm_andnot_si128(mask_sel, bs_lo));
__m128i out_hi = _mm_or_si128(_mm_and_si128(bm_hi, mask_sel), _mm_andnot_si128(mask_sel, bs_hi));
_mm_storeu_si128((__m128i*)(dst + i), out_lo);
_mm_storeu_si128((__m128i*)(dst + i + 8), out_hi);
}
if (i < len) {
widen_rotate90_u8_to_s16_bias127_scalar(src + i, dst + i, len - i);
}
}
#endif /* x86 */
/* NEON specializations */
#if defined(__ARM_NEON) || defined(__ARM_NEON__) || defined(__aarch64__)
static void widen_u8_to_s16_bias127_neon(const unsigned char *src, int16_t *dst, uint32_t len)
@@ -309,9 +361,9 @@ static void widen_rotate90_u8_to_s16_bias127_neon(const unsigned char *src, int1
vst1q_s16(dst + i, out_lo);
vst1q_s16(dst + i + 8, out_hi);
}
for (; i + 1 < len; i += 2) {
dst[i + 0] = (int16_t)src[i + 0] - 127;
dst[i + 1] = (int16_t)src[i + 1] - 127;
/* Tail: preserve rotation via scalar helper */
if (i < len) {
widen_rotate90_u8_to_s16_bias127_scalar(src + i, dst + i, len - i);
}
#else
/* ARMv7 NEON lacks vqtbl1q_u8; use scalar fallback for rotate+widen */
@@ -326,11 +378,13 @@ static void dsd_fme_init_runtime_dispatch_once(void)
int use_avx2 = 0;
int use_sse2 = 0;
int use_ssse3 = 0;
#if defined(__x86_64__) || defined(__i386__)
unsigned int eax=0, ebx=0, ecx=0, edx=0;
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
use_sse2 = (edx & bit_SSE2) ? 1 : 0;
use_ssse3 = (ecx & bit_SSSE3) ? 1 : 0;
int osxsave = (ecx & bit_OSXSAVE) ? 1 : 0;
int avx = (ecx & bit_AVX) ? 1 : 0;
if (osxsave && avx) {
@@ -383,9 +437,10 @@ static void dsd_fme_init_runtime_dispatch_once(void)
g_widen_rot_impl = &widen_rotate90_u8_to_s16_bias127_avx2;
return;
}
if (use_sse2) {
g_widen_impl = &widen_u8_to_s16_bias127_sse2;
g_widen_rot_impl = &widen_rotate90_u8_to_s16_bias127_sse2;
if (use_ssse3 || use_sse2) {
if (use_sse2) g_widen_impl = &widen_u8_to_s16_bias127_sse2;
if (use_ssse3) g_widen_rot_impl = &widen_rotate90_u8_to_s16_bias127_ssse3;
else g_widen_rot_impl = &widen_rotate90_u8_to_s16_bias127_sse2;
return;
}
#endif