tiny6410的ALSA编程出现IOCTR错误！
终端打印信息：
[root@FriendlyARM alsa]# ./alsa_readwrite
snd_pcm_open successed
snd_pcm_hw_params successed!
param output!
0
1
error from read: Inappropriate ioctl for device
应用程序代码：
/* Use the newer ALSA API */
#define ALSA_PCM_NEW_HW_PARAMS_API
/* All of the ALSA library API is defined
* in this header */
#include <alsa/asoundlib.h>
#include <stdio.h>
int main()
{
long loops;
int rc;
int size;
snd_pcm_t *handle;
snd_pcm_hw_params_t *params;
unsigned int val, val2;
int dir;
snd_pcm_uframes_t frames;
char *buffer;
/* Open PCM device for playback. */
rc = snd_pcm_open(&handle, "default",SND_PCM_STREAM_PLAYBACK, 0);
if (rc < 0) {
fprintf(stderr,"unable to open pcm device: %s\n",snd_strerror(rc));
exit(1);
}
else
{
printf("\tsnd_pcm_open successed\n");
}
/* Allocate a hardware parameters object. */
snd_pcm_hw_params_alloca(¶ms);
/* Fill it in with default values. */
snd_pcm_hw_params_any(handle, params);
/* Set the desired hardware parameters. */
/* Interleaved mode */
snd_pcm_hw_params_set_access(handle, params,SND_PCM_ACCESS_RW_INTERLEAVED);
/* Signed 16-bit little-endian format */
snd_pcm_hw_params_set_format(handle, params,SND_PCM_FORMAT_S16_LE);
/* Two channels (stereo) */
snd_pcm_hw_params_set_channels(handle, params, 2);
/* 44100 bits/second sampling rate (CD quality) */
val = 44100;
snd_pcm_hw_params_set_rate_near(handle,params, &val, 0);//&dir
/* Write the parameters to the driver */
rc = snd_pcm_hw_params(handle, params);
if (rc < 0) {
fprintf(stderr,"unable to set hw parameters: %s\n",snd_strerror(rc));
exit(1);
}
else
{
printf("\tsnd_pcm_hw_params successed!\n");
}
printf("\tparam output!\n");
/* Use a buffer large enough to hold one period */
snd_pcm_hw_params_get_period_size(params, &frames,
&dir);
size = frames * 4; /* 2 bytes/sample, 2 channels */
buffer = (char *) malloc(size);
/* We want to loop for 5 seconds */
snd_pcm_hw_params_get_period_time(params,
&val, &dir);
/* 5 seconds in microseconds divided by
* period time */
loops = 5000000 / val;
while (loops > 0)
{
loops--;
rc = snd_pcm_readi(handle, buffer, frames);
if (rc == -EPIPE)
{
/* EPIPE means overrun */
fprintf(stderr, "overrun occurred\n");
snd_pcm_prepare(handle);
}
else if (rc < 0)
{
fprintf(stderr,"error from read: %s\n",snd_strerror(rc));
}
else if (rc != (int)frames)
{
fprintf(stderr, "short read, read %d frames\n", rc);
}
rc = write(1, buffer, size);
if (rc != size)
fprintf(stderr,"short write: wrote %d bytes\n", rc);
}
snd_pcm_drain(handle);
snd_pcm_close(handle);
free(buffer);
return 0;
}
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