75 lines
1.6 KiB
C
75 lines
1.6 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include <string.h>
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static int usage()
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{
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fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
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return -1;
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}
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int r_main(int argc, char *argv[])
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{
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int width = 4, set = 0, fd;
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unsigned addr, value;
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void *page;
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if(argc < 2) return usage();
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if(!strcmp(argv[1], "-b")) {
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width = 1;
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argc--;
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argv++;
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} else if(!strcmp(argv[1], "-s")) {
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width = 2;
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argc--;
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argv++;
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}
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if(argc < 2) return usage();
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addr = strtoul(argv[1], 0, 16);
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if(argc > 2) {
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set = 1;
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value = strtoul(argv[2], 0, 16);
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}
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fd = open("/dev/mem", O_RDWR | O_SYNC);
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if(fd < 0) {
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fprintf(stderr,"cannot open /dev/mem\n");
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return -1;
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}
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page = mmap(0, 8192, PROT_READ | PROT_WRITE,
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MAP_SHARED, fd, addr & (~4095));
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if(page == MAP_FAILED){
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fprintf(stderr,"cannot mmap region\n");
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return -1;
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}
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switch(width){
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case 4: {
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unsigned *x = (unsigned*) (((unsigned) page) + (addr & 4095));
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if(set) *x = value;
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fprintf(stderr,"%08x: %08x\n", addr, *x);
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break;
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}
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case 2: {
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unsigned short *x = (unsigned short*) (((unsigned) page) + (addr & 4095));
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if(set) *x = value;
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fprintf(stderr,"%08x: %04x\n", addr, *x);
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break;
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}
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case 1: {
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unsigned char *x = (unsigned char*) (((unsigned) page) + (addr & 4095));
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if(set) *x = value;
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fprintf(stderr,"%08x: %02x\n", addr, *x);
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break;
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}
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}
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return 0;
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}
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