| | 1 | #define POLY 0x04c11db7 |
| | 2 | |
| | 3 | /* Theory of operation: |
| | 4 | * (arm-elf-objdump -b binary -m arm -M reg-names-raw -D RSB_S2_SINGLE.bin) |
| | 5 | * |
| | 6 | * 440: push {r4, r5, r6, r7, r8, r9, r10, r11, r14} |
| | 7 | * 444: mov r11, r0 |
| | 8 | * 448: mov r10, r1 |
| | 9 | * 44c: mov r14, r2 |
| | 10 | * 450: mov r6, #0 ; 0x0 |
| | 11 | * 454: b 0x4a0 |
| | 12 | * 458: add r3, r6, r10 |
| | 13 | * 45c: ldrb r3, [r3] |
| | 14 | * 460: lsl r3, r3, #24 |
| | 15 | * 464: eor r11, r11, r3 |
| | 16 | * 468: mov r5, #8 ; 0x8 |
| | 17 | * 46c: and r3, r11, #-2147483648 ; 0x80000000 |
| | 18 | * 470: cmp r3, #0 ; 0x0 |
| | 19 | * 474: beq 0x48c |
| | 20 | * 478: lsl r3, r11, #1 |
| | 21 | * 47c: ldr r12, [pc, #64] ; 0x4c4 |
| | 22 | * 480: eor r0, r3, r12 |
| | 23 | * 484: mov r11, r0 |
| | 24 | * 488: b 0x490 |
| | 25 | * 48c: lsl r11, r11, #1 |
| | 26 | * 490: sub r5, r5, #1 ; 0x1 |
| | 27 | * 494: cmp r5, #0 ; 0x0 |
| | 28 | * 498: bne 0x46c |
| | 29 | * 49c: add r6, r6, #1 ; 0x1 |
| | 30 | * 4a0: cmp r6, r14 |
| | 31 | * 4a4: blt 0x458 |
| | 32 | * 4a8: mov r0, r11 |
| | 33 | * 4ac: pop {r4, r5, r6, r7, r8, r9, r10, r11, r15} |
| | 34 | * 4c4: DATA: 0x04c11db7 |
| | 35 | */ |
| | 36 | |
| | 37 | unsigned int rsb_crc(unsigned int r11, unsigned char *r10, unsigned int r14) { |
| | 38 | unsigned int r6 = 0; |
| | 39 | unsigned int r3; |
| | 40 | int r5; |
| | 41 | |
| | 42 | while (r6 < r14) { |
| | 43 | r3 = (*(r6+r10)) << 24; |
| | 44 | r11 = r11 ^ r3; |
| | 45 | |
| | 46 | r5 = 8; |
| | 47 | |
| | 48 | do { |
| | 49 | r3 = r11 & 0x80000000; |
| | 50 | |
| | 51 | if (r3 != 0) { |
| | 52 | r3 = r11 << 1; |
| | 53 | r11 = r3 ^ POLY; |
| | 54 | } else { |
| | 55 | r11 = r11 << 1; |
| | 56 | } |
| | 57 | r5--; |
| | 58 | } while (r5); |
| | 59 | |
| | 60 | r6++; |
| | 61 | } |
| | 62 | |
| | 63 | return r11; |
| | 64 | } |
projects / rsbs2 / blame_incremental