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/*
* @defgroup _PHY_MODULATION_
* @ingroup _physical_layer_ref_implementation_
* @{
\section _phy_modulation_ OFDM Modulation Blocks
This section deals with basic functions for OFDM Modulation.
*/
#include "PHY/defs.h"
//static short temp2[2048*4] __attribute__((aligned(16)));
//#define DEBUG_OFDM_MOD
void normal_prefix_mod(int32_t *txdataF,int32_t *txdata,uint8_t nsymb,LTE_DL_FRAME_PARMS *frame_parms) {
uint8_t i;
int short_offset=0;
if ((2*nsymb) < frame_parms->symbols_per_tti)
short_offset = 1;
// printf("nsymb %d\n",nsymb);
for (i=0;i<((short_offset)+2*nsymb/frame_parms->symbols_per_tti);i++) {
#ifdef DEBUG_OFDM_MOD
printf("slot i %d (txdata offset %d, txoutput %p)\n",i,(i*(frame_parms->samples_per_tti>>1)),
txdata+(i*(frame_parms->samples_per_tti>>1)));
#endif
PHY_ofdm_mod(txdataF+(i*NUMBER_OF_OFDM_CARRIERS*frame_parms->symbols_per_tti>>1), // input
txdata+(i*frame_parms->samples_per_tti>>1), // output
frame_parms->log2_symbol_size, // log2_fft_size
1, // number of symbols
frame_parms->nb_prefix_samples0, // number of prefix samples
frame_parms->twiddle_ifft, // IFFT twiddle factors
frame_parms->rev, // bit-reversal permutation
CYCLIC_PREFIX);
#ifdef DEBUG_OFDM_MOD
printf("slot i %d (txdata offset %d)\n",i,OFDM_SYMBOL_SIZE_COMPLEX_SAMPLES0+(i*frame_parms->samples_per_tti>>1));
#endif
PHY_ofdm_mod(txdataF+NUMBER_OF_OFDM_CARRIERS+(i*NUMBER_OF_OFDM_CARRIERS*(frame_parms->symbols_per_tti>>1)), // input
txdata+OFDM_SYMBOL_SIZE_COMPLEX_SAMPLES0+(i*(frame_parms->samples_per_tti>>1)), // output
frame_parms->log2_symbol_size, // log2_fft_size
(short_offset==1) ? 1 :(frame_parms->symbols_per_tti>>1)-1,//6, // number of symbols
frame_parms->nb_prefix_samples, // number of prefix samples
frame_parms->twiddle_ifft, // IFFT twiddle factors
frame_parms->rev, // bit-reversal permutation
CYCLIC_PREFIX);
}
}
void PHY_ofdm_mod(int *input, /// pointer to complex input
int *output, /// pointer to complex output
unsigned char log2fftsize, /// log2(FFT_SIZE)
unsigned char nb_symbols, /// number of OFDM symbols
unsigned short nb_prefix_samples, /// cyclic prefix length
short *twiddle_ifft, /// pointer to precomputed twiddle table
unsigned short *rev, /// pointer to bit-reversal table
Extension_t etype /// type of extension
) {
static short temp[2048*4] __attribute__((aligned(16)));
unsigned short i,j;
short k;
volatile int *output_ptr=(int*)0;
int *temp_ptr=(int*)0;
void (*idft)(int16_t *,int16_t *, int);
switch (log2fftsize) {
case 7:
idft = idft128;
break;
case 8:
idft = idft256;
break;
case 9:
idft = idft512;
break;
case 10:
idft = idft1024;
break;
case 11:
idft = idft2048;
break;
default:
idft = idft512;
break;
}
#ifdef DEBUG_OFDM_MOD
msg("[PHY] OFDM mod (size %d,prefix %d) Symbols %d, input %p, output %p\n",
1<<log2fftsize,nb_prefix_samples,nb_symbols,input,output);
#endif
for (i=0;i<nb_symbols;i++){
#ifdef DEBUG_OFDM_MOD
msg("[PHY] symbol %d/%d (%p,%p -> %p)\n",i,nb_symbols,input,&input[i<<log2fftsize],&output[(i<<log2fftsize) + ((i)*nb_prefix_samples)]);
#endif
#ifndef NEW_FFT
fft((short *)&input[i<<log2fftsize],
temp,
twiddle_ifft,
rev,
log2fftsize,
log2fftsize/2, // normalized FFT (i.e. 1/sqrt(N) multiplicative factor)
0);
#else
idft((int16_t *)&input[i<<log2fftsize],
(log2fftsize==7) ? (int16_t *)temp : (int16_t *)&output[(i<<log2fftsize) + ((1+i)*nb_prefix_samples)],
1);
#endif
// write_output("fft_out.m","fftout",temp,(1<<log2fftsize)*2,1,1);
//memset(temp,0,1<<log2fftsize);
// Copy to frame buffer with Cyclic Extension
// Note: will have to adjust for synchronization offset!
switch (etype) {
case CYCLIC_PREFIX:
output_ptr = &output[(i<<log2fftsize) + ((1+i)*nb_prefix_samples)];
temp_ptr = (int *)temp;
// msg("Doing cyclic prefix method\n");
#ifndef NEW_FFT
for (j=0;j<((1<<log2fftsize)) ; j++) {
output_ptr[j] = temp_ptr[j];
output_ptr[j] = temp_ptr[2*j];
}
#else
if (log2fftsize==7) {
for (j=0;j<((1<<log2fftsize)) ; j++) {
output_ptr[j] = temp_ptr[j];
}
}
j=(1<<log2fftsize);
#endif
for (k=-1;k>=-nb_prefix_samples;k--) {
output_ptr[k] = output_ptr[--j];
}
break;
case CYCLIC_SUFFIX:
output_ptr = &output[(i<<log2fftsize)+ (i*nb_prefix_samples)];
temp_ptr = (int *)temp;
// msg("Doing cyclic suffix method\n");
for (j=0;j<(1<<log2fftsize) ; j++) {
output_ptr[j] = temp_ptr[2*j];
}
for (j=0;j<nb_prefix_samples;j++)
output_ptr[(1<<log2fftsize)+j] = output_ptr[j];
break;
case ZEROS:
break;
case NONE:
// msg("NO EXTENSION!\n");
output_ptr = &output[(i<<log2fftsize)];
temp_ptr = (int *)temp;
for (j=0;j<(1<<log2fftsize) ; j++) {
output_ptr[j] = temp_ptr[2*j];
}
break;
default:
break;
}
}
/*
printf("input %p, output %p, log2fftsize %d, nsymb %d\n",input,output,log2fftsize,nb_symbols);
for (i=0;i<16;i++)
printf("%d %d\n",((short *)input)[i<<1],((short *)input)[1+(i<<1)]);
printf("------\n");
for (i=0;i<16;i++)
printf("%d %d\n",((short *)output)[i<<1],((short *)output)[1+(i<<1)]);
*/
}
/** @} */