mirror of https://github.com/rusefi/rusefi-1.git
46 lines
1.3 KiB
ArmAsm
46 lines
1.3 KiB
ArmAsm
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/**
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* @file rusEfiStartup.S
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* rusEfi startup assembly
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*
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* We have ChibiOS '_crt0_entry' jumping here and then we jump back.
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* There is probably no stack at this point to invoke a method.
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*/
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// todo: I have no idea which lines are doing what
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// todo: one of these is resolving 'Error: lo register required -- `ldr SP,[R0,#0]'' :)
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.syntax unified
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.cpu cortex-m3
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.thumb
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.align 2
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.thumb_func
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// end of 'I have no idea'
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.global rusEfiAsboluteStartupMethod
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rusEfiAsboluteStartupMethod:
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// [rusefi][DFU][start]
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// Clive Two.Zero is the God of ST community forum
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// Device specific, if in doubt RTFM
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LDR R0, =0x2001FFF0 // End of SRAM for your CPU
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LDR R1, =0xDEADBEEF // magic value
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LDR R2, [R0, #0]
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STR R0, [R0, #0] // Invalidate
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CMP R2, R1
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BEQ UseDFU
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// DFU bootloader not needed, jump back to normal ChibiOS startup
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bl rusEfiAsboluteStartupMethodReturnPoint
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UseDFU:
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// AN2606 Application note
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// STM32 microcontroller system memory boot mode
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LDR R0, =0x40023844 // RCC_APB2ENR
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LDR R1, =0x00004000 // ENABLE SYSCFG CLOCK
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STR R1, [R0, #0]
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LDR R0, =0x40013800 // SYSCFG_MEMRMP
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LDR R1, =0x00000001 // MAP ROM AT ZERO
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STR R1, [R0, #0]
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LDR R0, =0x1FFF0000 // ROM BASE
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LDR SP,[R0, #0] // SP @ +0
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LDR R0,[R0, #4] // PC @ +4
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BX R0 // this jumps to DFU bootloader
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// I believe we are never executing this line
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// [rusefi][DFU][end]
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