sendout.c

dsp AD公司ADSP21的代码,里面有FFT FIR IIR EQULIZER G722_21F 等可以在项目中直接应用的代码.此代码的来源是ADI公司自己出版的书籍,此书在美国购得

/* DSP32c c-code to support circular output FIFO 5-17-94 LMS
10-31-94 CAC adapted to CAC boards
 */
#include <math.h>

/* length of integer input sample buffer */
#define FIFO_LENGTH 0x800
#define FIFO_LENGTH_BYTES 0x1000
#define FILL_FIFO 0x7D0
/*
#define FILL_FIFO 0x5
*/
#define FIFO_TOO_FULL  0x7E0


void out_int_enable();
void int_disable();
void flush();

extern short out_fifo_buffer[];
extern short in_fifo_buffer[];
short *out_pin = out_fifo_buffer;
short *in_pout = in_fifo_buffer;

/* global interrupt on flag */
int out_int_flag = 0;

asm void push_fifo(fltnum)
{
% mem fltnum;
        r2e = out_pin
        r4e = *r2
        r2e = *r2
        r1e = fltnum
        *r2 = a0 = int(*r1)
        r4e = r4 + 2
        r3e = out_fifo_buffer + FIFO_LENGTH_BYTES
        r4e - r3
        r3e = out_fifo_buffer
        if (ge) r4e = r3
        r2e = out_pin
        *r2 = r4e
}

asm int get_pin()
{
    r1e = out_pin
    r1e = *r1
    nop
}

asm int get_pout()
{
    r1e = r21
}

void sendout(x)
float x;
{

    register short *pin, *pout;
    register int samples_in_buff;

/* round and clip to 16 bits */
    push_fifo(x);

/* replaces: clip output to 16 bits
    j = (short)x;
    if(j > 32767) j = 32767;
    else if(j < -32768) j = -32768;
*/

/* keep checking the out pointer until pout gets close to pin */
/* do only while interrupts are enabled */
    pin = (short *) get_pin();

    if(out_int_flag) {

    /* determine number of samples in FIFO and 
    take care of circular buffer problems */
        do {
            pout = (short *) get_pout();

            if (pin > pout)
                samples_in_buff = pin - pout;
            else
                samples_in_buff = pin + FIFO_LENGTH - pout;
                
        } while(samples_in_buff > FIFO_TOO_FULL);
    }
    else {
         if(pin > (out_fifo_buffer + FILL_FIFO)) 
            out_int_enable();
    }
}

/* flush all samples out of the FIFO and then disable interrupts */

void flush()
{
    register short *pin,*pout;
    short j;
    float sample,delta;

    pin = (short *)get_pin();

    if(pin == out_fifo_buffer) pin = out_fifo_buffer + FIFO_LENGTH-1; else pin--;

/* slowly drop the output to zero to avoid pop */
    j = *pin;
    delta = fabs((float)j)/5000;
    if(delta <= 1.0) delta = 1.0;
    if(j >= 0) {
        sample = (float)j;
        while(sample > 0.0) {
            sendout(sample);
            sample -= delta;
        }
    }
    else {
        sample = (float)j;
        while(sample < 0.0) {
            sendout(sample);
            sample += delta;
        }
    }

    if(!out_int_flag) out_int_enable();

    pin = (short *) get_pin();

    if(pin == out_fifo_buffer) pin = out_fifo_buffer + FIFO_LENGTH-1; else pin--;

/* wait for end of samples */

    do {
        pout = (short *)get_pout();
    } while(pout != (pin - 1));

    int_disable();
}

void initialize_ioc()
{
#ifdef DBDADA
    asm("ioc = 0x30cc0");
#else
    asm("ioc = 0x30880");
#endif
}

/* interrupt enable function  */

void out_int_enable()
{
/* enable real-time serial output interrupt and serial output */
    asm("r1 = 0; obuf = r1;");
    initialize_ioc();
    asm("r1 = pcw; nop; r1 = r1 | 0x800; pcw = r1 ");

    out_int_flag = 1;
}

/* interrupt disable function - disables all serial i/o interrupts */

void int_disable()
{
/* disable real-time serial i/o interrupts and serial i/o */
    asm(" r1 = pcw"); 
    initialize_ioc();
    asm("r1 = r1 & 0xe7ff"); 
    asm("pcw = r1");
    out_int_flag = 0;
    out_pin = out_fifo_buffer;
    in_pout = in_fifo_buffer;
}