[rsbs2] / src / rsb-crc.c

#include <stdio.h>
#include <stdint.h>

#define POLY 0x04c11db7

uint32_t rsb_crc(uint32_t r11_crc, uint8_t *r10_buf, uint32_t r14_len) {
        uint32_t r6_pos = 0;
        uint32_t r3_data;
        int32_t r5_bit;

        while (r6_pos < r14_len) {
                r3_data = (*(r6_pos+r10_buf)) << 24;
                r11_crc = r11_crc ^ r3_data;

                r5_bit = 8;
                
                do {
                        r3_data = r11_crc & 0x80000000;

                        if (r3_data != 0) {
                                r3_data = r11_crc << 1;
                                r11_crc = r3_data ^ POLY;
                        } else {
                                r11_crc = r11_crc << 1;
                        }
                        r5_bit--;
                } while (r5_bit);

                r6_pos++;
        }

        return r11_crc;
}

uint32_t rsb_crc2(uint8_t *r0_buf, uint32_t r1_buflen, uint32_t r2_magic, uint32_t *crc_out) {
        uint32_t r4_len;
        uint32_t file_crc;

        r4_len = *(uint32_t*)(r0_buf + 0x20);

        if (*((uint32_t*)(r0_buf + 0x24)) != r2_magic)
                return 2; /* MAGIC does not match */
        
        if (r1_buflen < r4_len)
                return 3; /* image to small */
        
        *crc_out = ~rsb_crc(~0x0, r0_buf, r4_len);

        file_crc = *((uint32_t*)(r0_buf + r4_len));

        if (file_crc != *crc_out)
                return 4;

        return 0;
}