From 972ac24b5466e95d78f4af724c2f4e197f340eb5 Mon Sep 17 00:00:00 2001
From: Michael Gernoth <michael@gernoth.net>
Date: Wed, 28 Jan 2009 00:49:19 +0100
Subject: [PATCH] add something like the agilent crc implementation

---
 .gitignore |  3 ++
 Makefile   | 14 ++++++++
 firmware.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 rsb-crc.c  | 64 ++++++++++++++++++++++++++++++++++++
 rsb-crc.h  |  1 +
 5 files changed, 177 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 firmware.c
 create mode 100644 rsb-crc.c
 create mode 100644 rsb-crc.h

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6fe1a09
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+firmware
+firmware.o
+rsb-crc.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6122eea
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,14 @@
+CFLAGS=-Wall
+
+all: firmware 
+
+firmware: firmware.o rsb-crc.o
+
+firmware.o: firmware.c rsb-crc.h
+
+rsb-crc.o: rsb-crc.c rsb-crc.h
+
+clean:
+	rm -f firmware firmware.o rsb-crc.o
+
+.PHONY: all clean
diff --git a/firmware.c b/firmware.c
new file mode 100644
index 0000000..f8584c1
--- /dev/null
+++ b/firmware.c
@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <strings.h>
+#include "rsb-crc.h"
+
+struct fw_header {
+	unsigned int unknown[8];
+	unsigned int len;
+	char ident[4];
+	unsigned int offset;
+	char desc[128];
+};
+
+void parse_fw(unsigned char *fw, unsigned int off) {
+	struct fw_header *header = (struct fw_header*)(fw + off);
+	static unsigned int last_off;
+	int i;
+
+	printf("Address in file: 0x%08x, Difference to last: %u\n", off, off-last_off);
+	printf("Unknown: ");
+	for (i = 0; i < 8; i++)
+		printf("0x%08x ", header->unknown[i]);
+
+	printf("\n");
+
+	printf("Length: %u, possible next entry at: 0x%08x\n", header->len, off + header->len + 22);
+
+	printf("Identifier: %.4s\n", header->ident);
+
+	printf("Offset: 0x%08x\n", header->offset);
+
+	printf("Descriptiom: %s\n", header->desc);
+
+	printf("\n");
+	last_off = off;
+}
+
+int main(int argc, char **argv)
+{
+	struct stat statbuf;
+	unsigned char *fw;
+	int fd;
+	int remaining;
+	int ret;
+	unsigned int crc;
+
+	if (argc != 2) {
+		fprintf(stderr,"Syntax: %s firmware.bin\n", argv[0]);
+		exit(1);
+	}
+
+	if (stat(argv[1], &statbuf) == -1) {
+		perror("stat");
+		exit(1);
+	}
+
+	if ((fd = open(argv[1], O_RDONLY)) == -1) {
+		perror("open");
+		exit(1);
+	}
+
+	if ((fw = malloc(statbuf.st_size)) == NULL) {
+		perror("malloc");
+		exit(1);
+	}
+
+	bzero(fw, statbuf.st_size);
+
+	remaining = statbuf.st_size;
+
+	while(remaining) {
+		if ((ret = read(fd, fw + (statbuf.st_size - remaining), remaining)) == -1) {
+			perror("read");
+			exit(1);
+		}
+		remaining -= ret;
+	}
+
+#if 0
+	parse_fw(fw, 0x0);
+	parse_fw(fw, 0x555c0);
+	parse_fw(fw, 0x5940e);
+#endif
+
+	crc = rsb_crc(0, fw, statbuf.st_size-4);
+
+	printf("Length: %ld, Checksum: 0x%08x\n", statbuf.st_size-4, crc);
+
+	exit(0);
+}
diff --git a/rsb-crc.c b/rsb-crc.c
new file mode 100644
index 0000000..84b7fa2
--- /dev/null
+++ b/rsb-crc.c
@@ -0,0 +1,64 @@
+#define POLY 0x04c11db7
+
+/* 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
+ */
+
+unsigned int rsb_crc(unsigned int r11, unsigned char *r10, unsigned int r14) {
+	unsigned int r6 = 0;
+	unsigned int r3;
+	int r5;
+
+	while (r6 < r14) {
+		r3 = (*(r6+r10)) << 24;
+		r11 = r11 ^ r3;
+
+		r5 = 8;
+		
+		do {
+			r3 = r11 & 0x80000000;
+
+			if (r3 != 0) {
+				r3 = r11 << 1;
+				r11 = r3 ^ POLY;
+			} else {
+				r11 = r11 << 1;
+			}
+			r5--;
+		} while (r5);
+
+		r6++;
+	}
+
+	return r11;
+}
diff --git a/rsb-crc.h b/rsb-crc.h
new file mode 100644
index 0000000..94d327d
--- /dev/null
+++ b/rsb-crc.h
@@ -0,0 +1 @@
+unsigned int rsb_crc(unsigned int r11, unsigned char *r10, unsigned int r14);
-- 
2.39.2