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/* set volume of the startup chime in the PowerMac nvram.
Written by Matteo Frigo <athena@fftw.org>.
$Id: nvsetvol.c,v 1.1 2003/01/11 11:26:30 athena Exp $
This program is in the public domain.
*/
/* The volume is stored as a byte at address 8 in the parameter ram. */
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <asm/nvram.h>
#ifndef IOC_NVRAM_SYNC
#warning IOC_NVRAM_SYNC undefined -- update your headers
#define IOC_NVRAM_SYNC _IO('p', 0x43)
#endif
typedef struct {
unsigned char sig;
unsigned char cksum;
unsigned short len;
char name[12];
} header;
void die(const char *s) __attribute__((noreturn));
void die(const char *s)
{
perror(s);
exit(1);
}
void seek_pram(int fd, int offset)
{
if (lseek(fd, offset, SEEK_SET) < 0)
die("lseek");
}
// MSch: only works for newworld - oldworld have XPRAM at offset 0x1300 fixed.
int find_pram(int fd, int *size)
{
header buf;
int offset = 0;
int rc = 0;
while((rc = read(fd, &buf, sizeof(header))) == sizeof(header)) {
int sz = buf.len * 16;
// what's the sig in char?
// if (buf.sig == 0x1275) fprintf(stderr, "sig at offset %d rc %d buf.len %d buf.name %s \n", offset, rc, buf.len, buf.name);
// if (buf.sig == 0x5a) fprintf(stderr, "sig at offset %x rc %d buf.len %x buf.name %s \n", offset, rc, buf.len, buf.name);
// if (sz) fprintf(stderr, "offset %x rc %d sig %x buf.len %x buf.name %s \n", offset, rc, buf.sig, buf.len, buf.name);
if (!strncmp(buf.name, "APL,MacOS75", 11)) {
*size = sz - sizeof(header);
// fprintf(stderr, "XPRAM offset %x size %x\n", offset + sizeof(header), *size);
return offset + sizeof(header);
}
if (sz)
offset += sz;
else
offset += sizeof(header);
seek_pram(fd, offset);
}
// no Core99 style PRAM found - just assume hard coded values as set in kernel:
// XPRAM 0x1300
// NR 0x1400
// OF 0x1800
// TODO: use ioctl to get PRAM offset
// fprintf(stderr, "no NW PRAM found, assuming OW XPRAM offset 0x1300 size 0x100\n");
*size = 0x100;
return (0x1300);
// NOTREACHED
die("no PRAM found");
}
#define VOLADDR 8
int main(int argc, char *argv[])
{
int fd, offset, size, i;
char *buf;
fd = open("/dev/nvram", O_RDWR);
if (fd < 0) die("can't open /dev/nvram");
offset = find_pram(fd, &size);
buf = malloc(size);
if (!buf) die("can't malloc()");
seek_pram(fd, offset);
if (read(fd, buf, size) != size)
die("error reading /dev/nvram");
printf("current volume is %d\n", (unsigned char) buf[VOLADDR]);
#ifdef DEBUG_PRAM
for (i=0; i < size; i++) {
printf("cell %d : %d\n", i, (unsigned char) buf[i]);
}
#endif
if (argc > 1) {
buf[VOLADDR] = atoi(argv[1]);
seek_pram(fd, offset);
if (write(fd, buf, size) != size)
die("error writing /dev/nvram");
printf("new volume is %d\n", (unsigned char) buf[VOLADDR]);
}
ioctl(fd, IOC_NVRAM_SYNC);
close(fd);
return 0;
}
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