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Optimize PHY_ofdm_mod CYCLIC_PREFIX in case of incidentally aligned pointers

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It seems that the cyclic prefix is in most cases a multiple of 512 samples.
This means that in most cases the idft output pointer is already aligned and
there is no need to perform an extra memcpy. This saves the memcpy time in
most cyclic prefix insertion cases.
This commit is contained in:
Bartosz Podrygajlo
2024-12-16 15:04:03 +01:00
parent 31b8d98bb5
commit 1481d89dfd
1 changed files with 28 additions and 29 deletions
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openair1/PHY/MODULATION/ofdm_mod.c
+28 -29
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@@ -133,12 +133,6 @@ void PHY_ofdm_mod(int *input, /// pointer to complex input
if (nb_symbols == 0)
return;
int16_t temp[2 * 2 * 6144 * 4] __attribute__((aligned(32)));
int i, j;
volatile int *output_ptr = (int *)0;
int *temp_ptr = (int *)0;
idft_size_idx_t idft_size = get_idft(fftsize);
#ifdef DEBUG_OFDM_MOD
@@ -150,7 +144,7 @@ void PHY_ofdm_mod(int *input, /// pointer to complex input
output);
#endif
for (i = 0; i < nb_symbols; i++) {
for (int i = 0; i < nb_symbols; i++) {
#ifdef DEBUG_OFDM_MOD
printf("[PHY] symbol %d/%d offset %d (%p,%p -> %p)\n",
i,
@@ -162,57 +156,62 @@ void PHY_ofdm_mod(int *input, /// pointer to complex input
#endif
// on AVX2 need 256-bit alignment
idft(idft_size, (int16_t *)&input[i * fftsize], (int16_t *)temp, 1);
// Copy to frame buffer with Cyclic Extension
// Note: will have to adjust for synchronization offset!
switch (etype) {
case CYCLIC_PREFIX:
output_ptr = &output[(i * fftsize) + ((1 + i) * nb_prefix_samples)];
temp_ptr = (int *)temp;
// msg("Doing cyclic prefix method\n");
{
memcpy((void *)output_ptr, (void *)temp_ptr, fftsize << 2);
case CYCLIC_PREFIX: {
int *output_ptr = &output[(i * fftsize) + ((1 + i) * nb_prefix_samples)];
if ((uintptr_t)output_ptr % 32 == 0) {
// output ptr is aligned, do ifft inplace
idft(idft_size, (int16_t *)&input[i * fftsize], (int16_t *)output_ptr, 1);
} else {
// output ptr is not aligned, needs an extra memcpy
c16_t temp[fftsize] __attribute__((aligned(32)));
idft(idft_size, (int16_t *)&input[i * fftsize], (int16_t *)temp, 1);
memcpy((void *)output_ptr, (void *)temp, fftsize << 2);
}
// perform cyclic prefix insertion
memcpy((void *)&output_ptr[-nb_prefix_samples], (void *)&output_ptr[fftsize - nb_prefix_samples], nb_prefix_samples << 2);
break;
}
case CYCLIC_SUFFIX:
case CYCLIC_SUFFIX: {
c16_t temp[fftsize] __attribute__((aligned(32)));
idft(idft_size, (int16_t *)&input[i * fftsize], (int16_t *)temp, 1);
int *output_ptr = &output[(i * fftsize) + (i * nb_prefix_samples)];
output_ptr = &output[(i * fftsize) + (i * nb_prefix_samples)];
temp_ptr = (int *)temp;
int *temp_ptr = (int *)temp;
// msg("Doing cyclic suffix method\n");
for (j = 0; j < fftsize; j++) {
for (int j = 0; j < fftsize; j++) {
output_ptr[j] = temp_ptr[2 * j];
}
for (j = 0; j < nb_prefix_samples; j++)
for (int j = 0; j < nb_prefix_samples; j++)
output_ptr[fftsize + j] = output_ptr[j];
break;
}
case ZEROS:
break;
case NONE:
case NONE: {
c16_t temp[fftsize] __attribute__((aligned(32)));
idft(idft_size, (int16_t *)&input[i * fftsize], (int16_t *)temp, 1);
// msg("NO EXTENSION!\n");
output_ptr = &output[fftsize];
int *output_ptr = &output[fftsize];
temp_ptr = (int *)temp;
int *temp_ptr = (int *)temp;
for (j = 0; j < fftsize; j++) {
for (int j = 0; j < fftsize; j++) {
output_ptr[j] = temp_ptr[2 * j];
}
break;
}
default:
break;