git.zerfleddert.de Git - rsbs2/blob - rsb-crc.c

   1 #include <stdio.h>
   2
   3 #define POLY 0x04c11db7
   4
   5 unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int r14_len) {
   6         unsigned int r6_pos = 0;
   7         unsigned int r3_data;
   8         int r5_bit;
   9
  10         while (r6_pos < r14_len) {
  11                 r3_data = (*(r6_pos+r10_buf)) << 24;
  12                 r11_crc = r11_crc ^ r3_data;
  13
  14                 r5_bit = 8;
  15
  16                 do {
  17                         r3_data = r11_crc & 0x80000000;
  18
  19                         if (r3_data != 0) {
  20                                 r3_data = r11_crc << 1;
  21                                 r11_crc = r3_data ^ POLY;
  22                         } else {
  23                                 r11_crc = r11_crc << 1;
  24                         }
  25                         r5_bit--;
  26                 } while (r5_bit);
  27
  28                 r6_pos++;
  29         }
  30
  31         return r11_crc;
  32 }
  33
  34 unsigned int rsb_crc2(unsigned char *r0_buf, unsigned int r1_buflen, unsigned int r2_magic, unsigned int *crc_out) {
  35         unsigned int r4_len;
  36         unsigned int file_crc;
  37
  38         r4_len = *(unsigned int*)(r0_buf + 0x20);
  39
  40         if (*((unsigned int*)(r0_buf + 0x24)) != r2_magic)
  41                 return 2; /* MAGIC does not match */
  42
  43         if (r1_buflen < r4_len)
  44                 return 3; /* image to small */
  45
  46         *crc_out = ~rsb_crc(~0x0, r0_buf, r4_len);
  47
  48         file_crc = *((unsigned int*)(r0_buf + r4_len));
  49
  50         if (file_crc != *crc_out)
  51                 return 4;
  52
  53         return 0;
  54 }