Okay, this version of setvol (Empeg executable is attached, source is below) now restores the previous "saved" volume level (AC or DC) when run without any arguments. Otherwise, it takes a parameter 0..100 as before.

Enjoy!

#include <stdio.h>

#include <errno.h>

#include <fcntl.h>

#include <sys/ioctl.h>

#include <sys/soundcard.h>



#define MIXER "/dev/mixer"

#define STATE "/dev/empeg_state"

#define POWER "/proc/empeg_power"



static int Open (const char *path, int mode)

{

        int fd = open(path, mode);

        if (fd == -1) {

                perror(path);

                exit(errno);

        }

        return fd;

}



int main(int argc, char *argv[])

{

        int fd;

        int vol = -1;



        if (argc == 1) {

                unsigned char state[128], on_dc;

                // restore previous level for this powermode

                fd = Open(STATE, O_RDONLY);

                if (sizeof(state) != read(fd, state, sizeof(state))) {

                        perror(STATE);

                        exit(errno);

                }

                close(fd);

                fd = Open(POWER, O_RDONLY);

                if (1 != read(fd, &on_dc, 1)) {

                        perror(POWER);

                        exit(errno);

                }

                close(fd);

                on_dc &= 1;

                if (on_dc)

                        vol = (state[0x0d] >> 1);

                else

                        vol = ((state[0x0d] & 1) << 6) | (state[0xc] >> 2);

                printf("Saved %s volume was %u\n", on_dc ? "DC" : "AC", vol);

        } else if (argc != 2 || (vol = atoi(argv[1])) < 0 || vol > 100) {

                fprintf(stderr, "Usage:  %s volume   (where 0 <= volume <= 100)\n", argv[0]);

                exit(-1);

        }



        fd = Open(MIXER, O_WRONLY);

        vol |= (vol << 8);

        if (ioctl(fd, SOUND_MIXER_WRITE_VOLUME, &vol) == -1) {

                perror("SOUND_MIXER_WRITE_VOLUME");

                exit(errno);

        }

        close(fd);

        printf("Volume=%d\n", vol & 0xff);

        exit(0);

}