X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/rsbs2/blobdiff_plain/6fc57dcd5431aa5e19febfadb242de1e80f16c8f..3f4d6039fcf53e15e439597d6115b97ccd576457:/rsb-crc.c

diff --git a/rsb-crc.c b/rsb-crc.c
index 3fe5cbc..6a2bf99 100644
--- a/rsb-crc.c
+++ b/rsb-crc.c
@@ -2,41 +2,6 @@
 
 #define POLY 0x04c11db7
 
-/* Theory of operation:
- * (arm-elf-objdump -b binary -m arm -M reg-names-raw -D RSB_S2_SINGLE.bin)
- * Addresses: 0x4c4, 0x55ae0, 0x59734
- *
- * 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
- */
-
 unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int r14_len) {
 	unsigned int r6_pos = 0;
 	unsigned int r3_data;
@@ -66,128 +31,24 @@ unsigned int rsb_crc(unsigned int r11_crc, unsigned char *r10_buf, unsigned int
 	return r11_crc;
 }
 
-/* Second broken algorithm:
- *
- * 55a30: push    {r3, r4, r5, r6, r7, r8, r9, r14}
- * 55a34: bl      0x55a3c
- * 55a38: pop     {r3, r4, r5, r6, r7, r8, r9, r15}
- * 55a3c: mov     r8, #1  ; 0x1
- * 55a40: mov     r3, #-1073741824        ; 0xc0000000
- * 55a44: cmp     r0, r3
- * 55a48: ble     0x55ad8
- * 55a4c: mov     r3, #32 ; 0x20
- * 55a50: ldr     r4, [r3, r0]!
- * 55a54: mov     r8, #2  ; 0x2
- * 55a58: ldr     r5, [r3, #4]
- * 55a5c: cmp     r5, r2
- * 55a60: bne     0x55ad8
- * 55a64: mov     r8, #3  ; 0x3
- * 55a68: cmp     r1, r4
- * 55a6c: movscs  r5, #0  ; 0x0
- * 55a70: movscc  r5, #1  ; 0x1
- * 55a74: bne     0x55ad8
- * 55a78: mov     r8, #4  ; 0x4
- * 55a7c: mov     r3, r0
- * 55a80: add     r4, r0, r4
- * 55a84: mvn     r5, #0  ; 0x0
- * 55a88: ldr     r7, [pc, #80]   ; 0x55ae0
- * 55a8c: cmp     r3, r4
- * 55a90: bcs     0x55ac8
- * 55a94: bic     r9, r3, #3      ; 0x3
- * 55a98: ldr     r6, [r9]
- * 55a9c: and     r9, r3, #3      ; 0x3
- * 55aa0: lsl     r9, r9, #3
- * 55aa4: lsr     r6, r6, r9
- * 55aa8: eor     r5, r5, r6, lsl #24
- * 55aac: mov     r6, #8  ; 0x8
- * 55ab0: lsls    r5, r5, #1
- * 55ab4: eorcs   r5, r5, r7
- * 55ab8: subs    r6, r6, #1      ; 0x1
- * 55abc: bne     0x55ab0
- * 55ac0: add     r3, r3, #1      ; 0x1
- * 55ac4: b       0x55a8c
- * 55ac8: mvn     r5, r5
- * 55acc: ldr     r3, [r4]
- * 55ad0: subs    r3, r3, r5
- * 55ad4: moveq   r8, #0  ; 0x0
- * 55ad8: mov     r0, r8
- * 55adc: mov     r15, r14
- * 55ae0: DATA:   0x04c11db7
- */
-
-unsigned int rsb_crc2(unsigned char *r0_buf, unsigned int r1_buflen, unsigned int r2_magic, unsigned int *crc) {
-	int r8_ret = 1;
-	unsigned int r3 = 0xc0000000;
+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 r5;
-	unsigned int r6;
-	unsigned int r7_poly;
-	unsigned int r9;
-	unsigned int carry;
-
-#if 0
-	if (r0_buf <= r3)
-		return r8_ret;
-#endif
-
-	r3 = ((unsigned int)r0_buf) + 0x20;
-	r4_len = *((unsigned int*)r3);
-	printf("CRC: length: %d\n", r4_len);
-
-	r8_ret = 2;
-
-	r3 += 4;
-	r5 = *((unsigned int*)r3);
-
-	if (r5 != r2_magic)
-		return r8_ret;
-	
-	r8_ret = 3;
+	unsigned int file_crc;
 
-	if (r1_buflen >= r4_len) {
-		r5 = 0;
-	} else {
-		r5 = 1;
-	}
+	r4_len = *(unsigned int*)(r0_buf + 0x20);
 
-	if (r5 != 0)
-		return r8_ret;
+	if (*((unsigned int*)(r0_buf + 0x24)) != r2_magic)
+		return 2; /* MAGIC does not match */
 	
-	r8_ret = 4;
-
-	r3 = (unsigned int)r0_buf;
-	r4_len += r3;
+	if (r1_buflen < r4_len)
+		return 3; /* image to small */
 	
-	r5 = ~0x0;
-
-	r7_poly = POLY;
-
-	while (r3 < r4_len) {
-		r9 = r3 & (~0x3);
-		r6 = *((unsigned int*)r9);
-		r9 = r3 & 0x3;
-		r9 = r9 << 0x3;
-		r6 = r6 >> r9;
-		r5 = r5 ^ (r6 << 24);
-		r6 = 0x8;
-
-		do {
-			carry = r5 & 0x80000000;
-			r5 = r5 << 1;
-			if (carry)
-				r5 = r5 ^ r7_poly;
-			r6--;
-		} while(r6);
-		r3++;
-	}
-
-	r5 = ~r5;
-	*crc = r5;
+	*crc_out = ~rsb_crc(~0x0, r0_buf, r4_len);
 
-	r3 = *((unsigned int*)r4_len);
+	file_crc = *((unsigned int*)(r0_buf + r4_len));
 
-	if (r3 == r5)
-		r8_ret = 0;
+	if (file_crc != *crc_out)
+		return 4;
 
-	return r8_ret;
+	return 0;
 }