add possibly working compression algorithm

[rsbs2] / rsb-crc.c

diff --git a/rsb-crc.c b/rsb-crc.c
index fa40c498099e3b3838e8e325f00b844940287bc1..6a2bf99540be9dfc519a59c7743032c6a6e3ba8f 100644 (file)
--- a/rsb-crc.c
+++ b/rsb-crc.c
@@ -1,38 +1,6 @@
-#define POLY 0x04c11db7
+#include <stdio.h>

 
 

-/* Theory of operation:
- * (arm-elf-objdump -b binary -m arm -M reg-names-raw -D RSB_S2_SINGLE.bin)
- *
- * 440: push  {r4, r5, r6, r7, r8, r9, r10, r11, r14}
- * 444: mov   r11, r0
- * 448: mov   r10, r1
- * 44c: mov   r14, r2
- * 450: mov   r6, #0   ; 0x0
- * 454: b     0x4a0
- * 458: add   r3, r6, r10
- * 45c: ldrb  r3, [r3]
- * 460: lsl   r3, r3, #24
- * 464: eor   r11, r11, r3
- * 468: mov   r5, #8   ; 0x8
- * 46c: and   r3, r11, #-2147483648    ; 0x80000000
- * 470: cmp   r3, #0   ; 0x0
- * 474: beq   0x48c
- * 478: lsl   r3, r11, #1
- * 47c: ldr   r12, [pc, #64]   ; 0x4c4
- * 480: eor   r0, r3, r12
- * 484: mov   r11, r0
- * 488: b     0x490
- * 48c: lsl   r11, r11, #1
- * 490: sub   r5, r5, #1       ; 0x1
- * 494: cmp   r5, #0           ; 0x0
- * 498: bne   0x46c
- * 49c: add   r6, r6, #1       ; 0x1
- * 4a0: cmp   r6, r14
- * 4a4: blt   0x458
- * 4a8: mov   r0, r11
- * 4ac: pop   {r4, r5, r6, r7, r8, r9, r10, r11, r15}
- * 4c4: DATA: 0x04c11db7
- */
+#define POLY 0x04c11db7

 
 unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int r14_len) {
        unsigned int r6_pos = 0;
 
 unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int r14_len) {
        unsigned int r6_pos = 0;


@@ -62,3 +30,25 @@ unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int
 
        return r11_crc;
 }
 
        return r11_crc;
 }

+
+unsigned int rsb_crc2(unsigned char *r0_buf, unsigned int r1_buflen, unsigned int r2_magic, unsigned int *crc_out) {
+       unsigned int r4_len;
+       unsigned int file_crc;
+
+       r4_len = *(unsigned int*)(r0_buf + 0x20);
+
+       if (*((unsigned int*)(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 = *((unsigned int*)(r0_buf + r4_len));
+
+       if (file_crc != *crc_out)
+               return 4;
+
+       return 0;
+}