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Begin porting FIR Filter for GMSK Modem

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This commit is contained in:
Ed Gonzalez 2015-06-02 14:51:33 -05:00
parent fc8de37bd6
commit ef467c41aa
2 changed files with 100 additions and 1 deletions
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82
DSP_API/ThumbDV/gmsk_modem.c
View file

@ -24,11 +24,16 @@
*
* ************************************************************************** */
/* Demod Section */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "DStarDefines.h"
#include "gmsk_modem.h"
#include "common.h"
/* Demod Section */
const float DEMOD_COEFFS_TABLE[] = {
/* 2400 Hz */
-0.000153959924563F, 0.000000000000000F, 0.000167227768379F, 0.000341615513437F,
@ -152,3 +157,78 @@ uint32 gmsk_encode(GMSK_MOD mod, BOOL bit, float * buffer, unsigned int length)
}
/* Init */
FIR_FILTER gmsk_createFilter(const float * taps, uint32 length)
{
FIR_FILTER filter = (FIR_FILTER) safe_malloc(sizeof(fir_filter));
filter->length = length;
filter->buf_len = 20 * length;
filter->taps = (float *) safe_malloc(length * sizeof(float));
memcpy(filter->taps, taps, length * sizeof(float));
filter->buffer = (float *) safe_malloc(filter->buf_len * sizeof(float));
filter->pointer = length;
return filter;
}
void gmsk_destroyFilter(FIR_FILTER filter)
{
if ( filter == NULL ) {
output(ANSI_RED "NULL FIlter object\n"ANSI_WHITE ) ;
return;
}
safe_free(filter->taps);
safe_free(filter->buffer);
safe_free(filter);
}
GMSK_DEMOD gmsk_createDemodulator(void)
{
GMSK_DEMOD demod = (GMSK_DEMOD) safe_malloc(sizeof(gmsk_demod));
demod->m_pll = 0;
demod->m_prev = FALSE;
demod->m_invert = FALSE;
demod->filter = gmsk_createFilter(DEMOD_COEFFS_TABLE, DEMOD_COEFFS_LENGTH);
return demod;
}
GMSK_MOD gmsk_createModulator(void)
{
GMSK_MOD mod = (GMSK_MOD) safe_malloc(sizeof(gmsk_mod));
mod->m_invert = FALSE;
mod->filter = gmsk_createFilter(MOD_COEFFS_TABLE, MOD_COEFFS_LENGTH);
return mod;
}
void gmsk_destroyDemodulator(GMSK_DEMOD demod )
{
if ( demod == NULL ) {
output(ANSI_RED "NULL GMSK_DEMOD\n" ANSI_WHITE);
return;
}
gmsk_destroyFilter(demod->filter);
safe_free(demod);
}
void gmsk_destroyModulator(GMSK_MOD mod )
{
if ( mod == NULL ) {
output(ANSI_RED "NULL GMSK_MOD\n" ANSI_WHITE);
return;
}
gmsk_destroyFilter(mod->filter);
safe_free(mod);
}

19
DSP_API/ThumbDV/gmsk_modem.h
View file

@ -33,22 +33,41 @@ enum DEMOD_STATE {
DEMOD_UNKNOWN
};
typedef struct _fir_filter
{
float * taps;
uint32 length;
float * buffer;
uint32 buf_len;
uint32 pointer;
}fir_filter, * FIR_FILTER ;
/* Used to hold state information for a GMSK Demodulator object */
typedef struct _gmsk_demod
{
uint32 m_pll;
BOOL m_prev;
BOOL m_invert;
FIR_FILTER filter;
} gmsk_demod, * GMSK_DEMOD;
typedef struct _gmsk_mod
{
BOOL m_invert;
FIR_FILTER filter;
} gmsk_mod, * GMSK_MOD;
uint32 gmsk_encode(GMSK_MOD mod, BOOL bit, float * buffer, unsigned int length);
enum DEMOD_STATE gmsk_decode(GMSK_DEMOD demod, float val);
void gmskDemod_reset(GMSK_DEMOD demod );
GMSK_MOD gmsk_createModulator(void);
GMSK_DEMOD gmsk_createDemodulator(void);
void gmsk_destroyModulator(GMSK_MOD mod );
void gmsk_destroyDemodulator(GMSK_DEMOD demod );
#endif /* THUMBDV_GMSK_MODEM_H_ */