void FirmwareStart(){ asm( "LDR R3, =0xC02200bc\n" "MOV R2, #0x44\n" "STR R2, [R3]\n"// looks like idle cycle is required for proper shutdown "MOV R3, #0x8000\n""idle_cycle:" "SUB R3, R3, #1\n" "CMP R3, #0\n" "BNE idle_cycle\n"// ordinary startup... "MOV SP, #0x1900\n" "MOV R11, #0\n" "MRS R1, CPSR\n" "BIC R1, R1, #0x3F\n" "ORR R1, R1, #0xD3\n" "MSR CPSR_cf, R1\n" "LDR R2, =0xC0200000\n" "MOV R1, #0xFFFFFFFF\n" "STR R1, [R2,#0x10C]\n" "STR R1, [R2,#0xC]\n" "STR R1, [R2,#0x1C]\n" "STR R1, [R2,#0x2C]\n" "STR R1, [R2,#0x3C]\n" "STR R1, [R2,#0x4C]\n" "STR R1, [R2,#0x5C]\n" "STR R1, [R2,#0x6C]\n" "STR R1, [R2,#0x7C]\n" "STR R1, [R2,#0x8C]\n" "STR R1, [R2,#0x9C]\n" "STR R1, [R2,#0xAC]\n" "STR R1, [R2,#0xBC]\n" "STR R1, [R2,#0xCC]\n" "STR R1, [R2,#0xDC]\n" "STR R1, [R2,#0xEC]\n" "STR R1, [R2,#0xFC]\n" "MOV R1, #0x78\n" "MCR p15, 0, R1,c1,c0\n" "MOV R1, #0\n" "MCR p15, 0, R1,c7,c10, 4\n" "MCR p15, 0, R1,c7,c5\n" "MCR p15, 0, R1,c7,c6\n" "MOV R2, #0x40000000\n" "ORR R1, R2, #6\n" "MCR p15, 0, R1,c9,c1\n" "ORR R1, R1, #6\n" "MCR p15, 0, R1,c9,c1, 1\n" "MRC p15, 0, R1,c1,c0\n" "ORR R1, R1, #0x50000\n" "MCR p15, 0, R1,c1,c0\n" "MOV R3, #0xFF0\n" "LDR R1, =0x12345678\n" "ADD R3, R3, #0x4000000C\n" "STR R1, [R3]\n" "MOV SP, #0x1900\n" "MOV LR, PC\n" "LDR PC, =0xffc00000\n" );}
From personal experience there is nothing like porting chdk to a new camera. It may be worth doing an old camera from scratch to get the idea of all the ins and outs. That way if you need assistance you can look at the current port and see the answer.Harpo
What I am trying to do here is a side project of mine. I want to be able to modify the firmware so that I can remove those annoying error checks that won't let me start the camera without lenses, as well as the long exposure hack and possibly other cool things. But it will probably not work in conjunction with CHDK, however some people might find it useful (if I manage to get it to work, that is).
A big problem is that you have no way of knowing whether a constant loaded from memory is an address or not. Analyzing the code to determine this is non-trivial.
Well, let's say the code starts at 0xffc00000 and ends at ffff0000 and you find a memory location that you know for sure is accessed from the code, and holds a value like ffc03620. What else could it be if not an address?
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