signal processing architecture in C

streamer.c

/*
 * design pattern of descriptor based signal processing framework
 * based on ideas of mediastreamer2 library
 * 2015 by OL
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>


/*
 * --- primitive quasi static memory management ---
 */

typedef struct pa_dsp_heap_struct {
  void* heapPtr;
  void* heapLimit;
} *PA_DSP_HEAP_HANDLE;

void* pa_dsp_alloc( PA_DSP_HEAP_HANDLE hh, int size, int align_addr_to_power_of  )
{
  void* ptr = hh->heapPtr;
  int offset = ((unsigned long)ptr) % align_addr_to_power_of;
  ptr += offset;
  assert( (hh->heapPtr += (size+offset)) < hh->heapLimit );

  return ptr;
}

void pa_dsp_free( PA_DSP_HEAP_HANDLE hh, void* address  )
{
}


/*
 * --- filter data structures and operations ---
 */
struct pa_dsp_filt_struct;
typedef void  (* PA_DSP_FILT_FUNC)( struct pa_dsp_filt_struct * );
typedef void  (* PA_DSP_INIT_FUNC)( struct pa_dsp_filt_struct *, PA_DSP_HEAP_HANDLE );

typedef struct pa_dsp_filt_desc_struct {
	int   id;	       /* the id declared in allfilters.h */
	char* name;      /* filter name */
	char* text;      /*some descriptive text*/
  int   frame_size;
  int   ninputs;
  int   noutputs;
  void* data;
  PA_DSP_INIT_FUNC  init;
  PA_DSP_FILT_FUNC  config;
  PA_DSP_INIT_FUNC  release;
  PA_DSP_FILT_FUNC  proc;
} PA_DSP_FILT_DESC;


typedef struct pa_dsp_filt_struct {
  PA_DSP_FILT_DESC* desc;
  void** inp;
  void** out;
  void*  state;
} PA_DSP_FILT;


void pa_dsp_connect_inputs( PA_DSP_FILT* filt1, PA_DSP_FILT* filt2 )
{
  int i;

  assert( filt1->desc->frame_size == filt2->desc->frame_size );
  assert( filt1->desc->noutputs == filt2->desc->ninputs );

  for( i=0; i<filt1->desc->noutputs; ++i)
    filt1->out[i] = filt2->inp[i];
}



typedef struct pa_dsp_filt_lst_struct {
  PA_DSP_FILT* filt;
  struct pa_dsp_filt_lst_struct *next;
} PA_DSP_FILT_LST;


/*
 * --- filter 1 ---
 */

typedef struct filt1_conf_struct {
  int a;
  int b;
} FILT1_CONF;

static FILT1_CONF filt1_conf = { 1, 2 };



static void init1( PA_DSP_FILT* filt, PA_DSP_HEAP_HANDLE heapHandle )
{
  printf("initialize filter 1 ...\n");

  filt->inp = pa_dsp_alloc( heapHandle, sizeof(void*), 2 );
  filt->out = pa_dsp_alloc( heapHandle, sizeof(void*), 2 );
  filt->inp[0] = pa_dsp_alloc( heapHandle, filt->desc->frame_size, 2  );
}

static void release1( PA_DSP_FILT* filt, PA_DSP_HEAP_HANDLE heapHandle  )
{
  printf("release filter 1 ...\n");
}

static void proc1( PA_DSP_FILT* filt )
{
  int i;
  int* inp = (int *)filt->inp[0];
  int* out = (int *)filt->out[0];

  printf("processing filter1, first three input elements: ");

  for( i=0; i<3; ++i ) {
    printf("%d, ", inp[i] );
    out[i] = 1 + inp[i];
  }

  printf("\n");
}


PA_DSP_FILT_DESC filt_desc1 = {
  .id = 1,
  .name = "filt1",
  .frame_size = 100,
  .ninputs = 1,
  .noutputs = 1,
  .init = init1,
  .release = release1,
  .proc = proc1,
  .data = &filt1_conf,
};




/*
 * --- filter 2 ---
 */

typedef struct filt2_conf_struct {
  short c;
  int d;
} FILT2_CONF;

static FILT2_CONF filt2_conf = { 3, 4 };



static void init2( PA_DSP_FILT* filt, PA_DSP_HEAP_HANDLE heapHandle )
{
  printf("initialize filter 2 ...\n");

  filt->inp = pa_dsp_alloc( heapHandle, sizeof(void*), 2 );
  filt->out = pa_dsp_alloc( heapHandle, sizeof(void*), 2 );
  filt->inp[0] = pa_dsp_alloc( heapHandle, filt->desc->frame_size, 2  );
}

static void release2( PA_DSP_FILT* filt, PA_DSP_HEAP_HANDLE heapHandle  )
{
  printf("release filter 2 ...\n");
}

static void proc2( PA_DSP_FILT* filt )
{
  int i;
  int* inp = (int *)filt->inp[0];
  int* out = (int *)filt->out[0];

  printf("processing filter2, first three input elements: ");

  for( i=0; i<3; ++i ) {
    printf("%d, ", inp[i] );
    out[i] = 2 * inp[i];
  }

  printf("\n");
}


PA_DSP_FILT_DESC filt_desc2 = {
  .id = 2,
  .name = "filt2",
  .frame_size = 100,
  .ninputs = 1,
  .noutputs = 1,
  .init = init2,
  .release = release2,
  .proc = proc2,
  .data = &filt2_conf,
};








int main()
{
  #define HEAPSIZE 1000
  int heap[HEAPSIZE/sizeof(int)];
  struct pa_dsp_heap_struct heapStruct = { .heapPtr = &heap, .heapLimit = &heap + HEAPSIZE };
  PA_DSP_HEAP_HANDLE heapHandle = &heapStruct;

  PA_DSP_FILT_LST* pList;

  int* in;
  int out[100];

  int i;

  /*
   * --- list of filters ---
   */

  PA_DSP_FILT filt1 = { .desc = &filt_desc1 };
  PA_DSP_FILT filt2 = { .desc = &filt_desc2 };

  PA_DSP_FILT_LST filter_queue[2];

  filter_queue[0].filt = &filt1; filter_queue[0].next = &filter_queue[1];
  filter_queue[1].filt = &filt2; filter_queue[1].next = NULL;



  /* initialize and connect filters */
  for( pList =  filter_queue; pList != NULL; pList = pList->next )
    pList->filt->desc->init( pList->filt, heapHandle );

  pa_dsp_connect_inputs( &filt1, &filt2 );
  filt2.out[0] = out;



  /* initialize first filter's input with some values */
  for( i=0, in=(int*)filt1.inp[0]; i<3; ++i )
    in[i] = i;


  /* start process */
  for( pList =  filter_queue; pList != NULL; pList = pList->next )
    pList->filt->desc->proc( pList->filt );


  /* print output */
  printf("processing result: ");
  for( i=0; i<3; ++i ) {
    printf("%d, ", out[i] );
  }
  printf("\n");


  /* release filters */
  for( pList =  filter_queue; pList != NULL; pList = pList->next )
    pList->filt->desc->release( pList->filt, heapHandle );

  return 0;
}