163 lines
4.8 KiB
ArmAsm
163 lines
4.8 KiB
ArmAsm
/* *************************************************************
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crt.s STARTUP ASSEMBLY CODE
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-----------------------
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Module includes the interrupt vectors and start-up code.
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****************************************************************/
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/* Stack Sizes */
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.set UND_STACK_SIZE, 0x00000004 /* stack for "undefined instruction" interrupts is 4 bytes */
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.set ABT_STACK_SIZE, 0x00000004 /* stack for "abort" interrupts is 4 bytes */
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.set FIQ_STACK_SIZE, 0x00000010 /* stack for "FIQ" interrupts is 4 bytes */
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.set IRQ_STACK_SIZE, 0X00000020 /* stack for "IRQ" normal interrupts is 4 bytes */
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.set SVC_STACK_SIZE, 0x00000010 /* stack for "SVC" supervisor mode is 4 bytes */
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/* Standard definitions of Mode bits and Interrupt (I & F) flags in PSRs (program status registers) */
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.set MODE_USR, 0x10 /* Normal User Mode */
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.set MODE_FIQ, 0x11 /* FIQ Processing Fast Interrupts Mode */
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.set MODE_IRQ, 0x12 /* IRQ Processing Standard Interrupts Mode */
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.set MODE_SVC, 0x13 /* Supervisor Processing Software Interrupts Mode */
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.set MODE_ABT, 0x17 /* Abort Processing memory Faults Mode */
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.set MODE_UND, 0x1B /* Undefined Processing Undefined Instructions Mode */
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.set MODE_SYS, 0x1F /* System Running Priviledged Operating System Tasks Mode */
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.set I_BIT, 0x80 /* when I bit is set, IRQ is disabled (program status registers) */
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.set F_BIT, 0x40 /* when F bit is set, FIQ is disabled (program status registers) */
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.text
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.arm
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.global Reset_Handler
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.global _startup
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.func _startup
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_startup:
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# Exception Vectors
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_vectors: ldr PC, Reset_Addr
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ldr PC, Undef_Addr
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ldr PC, SWI_Addr
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ldr PC, PAbt_Addr
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ldr PC, DAbt_Addr
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nop /* Reserved Vector (holds Philips ISP checksum) */
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ldr PC, [PC,#-0xFF0] /* see page 71 of "Insiders Guide to the Philips ARM7-Based Microcontrollers" by Trevor Martin */
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ldr PC, FIQ_Addr
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Reset_Addr: .word Reset_Handler /* defined in this module below */
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Undef_Addr: .word UNDEF_Routine /* defined in main.c */
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SWI_Addr: .word SWI_Routine /* defined in main.c */
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PAbt_Addr: .word UNDEF_Routine /* defined in main.c */
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DAbt_Addr: .word UNDEF_Routine /* defined in main.c */
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IRQ_Addr: .word IRQ_Routine /* defined in main.c */
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FIQ_Addr: .word FIQ_Routine /* defined in main.c */
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.word 0 /* rounds the vectors and ISR addresses to 64 bytes total */
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# Reset Handler
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Reset_Handler:
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/* Setup a stack for each mode - note that this only sets up a usable stack
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for User mode. Also each mode is setup with interrupts initially disabled. */
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ldr r0, =_stack_end
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msr CPSR_c, #MODE_UND|I_BIT|F_BIT /* Undefined Instruction Mode */
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mov sp, r0
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sub r0, r0, #UND_STACK_SIZE
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msr CPSR_c, #MODE_ABT|I_BIT|F_BIT /* Abort Mode */
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mov sp, r0
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sub r0, r0, #ABT_STACK_SIZE
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msr CPSR_c, #MODE_FIQ|I_BIT|F_BIT /* FIQ Mode */
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mov sp, r0
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sub r0, r0, #FIQ_STACK_SIZE
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msr CPSR_c, #MODE_IRQ|I_BIT|F_BIT /* IRQ Mode */
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mov sp, r0
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sub r0, r0, #IRQ_STACK_SIZE
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msr CPSR_c, #MODE_SVC|I_BIT|F_BIT /* Supervisor Mode */
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mov sp, r0
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sub r0, r0, #SVC_STACK_SIZE
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msr CPSR_c, #MODE_SYS|F_BIT /* User Mode */
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mov sp, r0
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/* set up pins and membanks */
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ldr r0, = PINSEL2
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ldr r2, =0xD6041D4
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str r2, [r0]
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ldr r1, =0x10000420
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ldr r0,=BCFG0
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str r1,[r0]
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str r1,[r0,#0x08]
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/* copy .data section (Copy from ROM to RAM) */
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ldr R1, =_etext
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ldr R2, =_data
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ldr R3, =_edata
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1: cmp R2, R3
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ldrlo R0, [R1], #4
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strlo R0, [R2], #4
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blo 1b
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/* Clear .bss section (Zero init) */
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mov R0, #0
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ldr R1, =_bss_start
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ldr R2, =_bss_end
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2: cmp R1, R2
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strlo R0, [R1], #4
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blo 2b
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/* set up the pll */
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ldr r0, =0xe01fc000
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ldr r2, =0xaa
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ldr r3, =0x55
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ldr r1, =0x03
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str r1, [r0,#0x80]
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ldr r1, =0x0
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str r1, [r0,#0x100]
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ldr r1, =0x42
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str r1,[r0,#0x84]
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str r2, [r0,#0x8c]
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str r3, [r0,#0x8c]
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ldr r2, =IO0PIN
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mov r3, #0x10
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str r3, [r2,#0xc]
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ldr r3, [r2,#8]
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bic r3, r3, #0x10
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str r3, [r2,#8]
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ldr r1, =0xc42
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ldr r0, =BCFG1
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str r1, [r0]
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ldr r2, =PINSEL0
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ldr r3, [r2,#0x14]
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orr r3, r3, #0x800
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str r3, [r2,#0x14]
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ldr r3, [r2,#0x14]
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orr r3, r3, #0x800000
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str r3, [r2,#0x14]
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/* Enter the C code */
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mov r0,#0
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mov r1,r0
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mov r2,r0
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mov fp,r0
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mov r7,r0
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ldr r10,=main
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mov lr,pc
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bx r10
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.endfunc
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entry_mask: .word 0x4FFFFFFF /* defined in this module below */
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.end
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