1#include <stdio.h>
2#include <stdlib.h>
3#include <sys/mman.h>
4#include <fcntl.h>
5#include <string.h>
6
7static int usage()
8{
9    fprintf(stderr,"r [-b|-s] <address> [<value>]\n");
10    return -1;
11}
12
13int r_main(int argc, char *argv[])
14{
15    int width = 4, set = 0, fd;
16    unsigned addr, value, endaddr = 0;
17    unsigned long mmap_start, mmap_size;
18    void *page;
19    char *end;
20
21    if(argc < 2) return usage();
22
23    if(!strcmp(argv[1], "-b")) {
24        width = 1;
25        argc--;
26        argv++;
27    } else if(!strcmp(argv[1], "-s")) {
28        width = 2;
29        argc--;
30        argv++;
31    }
32
33    if(argc < 2) return usage();
34    addr = strtoul(argv[1], 0, 16);
35
36    end = strchr(argv[1], '-');
37    if (end)
38        endaddr = strtoul(end + 1, 0, 16);
39
40    if (!endaddr)
41        endaddr = addr + width - 1;
42
43    if (endaddr <= addr) {
44        fprintf(stderr, "invalid end address\n");
45        return -1;
46    }
47
48    if(argc > 2) {
49        set = 1;
50        value = strtoul(argv[2], 0, 16);
51    }
52
53    fd = open("/dev/mem", O_RDWR | O_SYNC);
54    if(fd < 0) {
55        fprintf(stderr,"cannot open /dev/mem\n");
56        return -1;
57    }
58
59    mmap_start = addr & ~(PAGE_SIZE - 1);
60    mmap_size = endaddr - mmap_start + 1;
61    mmap_size = (mmap_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
62
63    page = mmap(0, mmap_size, PROT_READ | PROT_WRITE,
64                MAP_SHARED, fd, mmap_start);
65
66    if(page == MAP_FAILED){
67        fprintf(stderr,"cannot mmap region\n");
68        return -1;
69    }
70
71    while (addr <= endaddr) {
72        switch(width){
73        case 4: {
74            unsigned *x = (unsigned*) (((unsigned) page) + (addr & 4095));
75            if(set) *x = value;
76            fprintf(stderr,"%08x: %08x\n", addr, *x);
77            break;
78        }
79        case 2: {
80            unsigned short *x = (unsigned short*) (((unsigned) page) + (addr & 4095));
81            if(set) *x = value;
82            fprintf(stderr,"%08x: %04x\n", addr, *x);
83            break;
84        }
85        case 1: {
86            unsigned char *x = (unsigned char*) (((unsigned) page) + (addr & 4095));
87            if(set) *x = value;
88            fprintf(stderr,"%08x: %02x\n", addr, *x);
89            break;
90        }
91        }
92        addr += width;
93    }
94    return 0;
95}
96