206 lines
4.3 KiB
ArmAsm
206 lines
4.3 KiB
ArmAsm
#include "mips.h"
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.extern main
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.global start
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.set mips32r2
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.set noreorder
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.section .init.text,"ax",%progbits
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start:
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di # disable interrupts
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bltzal zero, load_addr # ra = PC + 8, branch not taken
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nop
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load_addr:
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addiu v0, ra, -12 # calc real load address
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# account for branch delay slot
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# and very first 'di' instruction
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la t0, 0x80000000 # an idx op should use an unmappable address
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ori t1, t0, 0x4000 # 16kB cache
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mtc0 zero, C0_TAGLO
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mtc0 zero, C0_TAGHI
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cache_init_loop:
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cache ICIndexStTag, 0(t0) # index store icache tag
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cache DCIndexStTag, 0(t0) # index store dcache tag
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bne t0, t1, cache_init_loop
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addiu t0, t0, 0x10
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li t0, 3 # enable cache for kseg0 accesses
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mtc0 t0, C0_CONFIG
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ehb
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la t0, relocstart
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la t1, relocend
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beq t0, v0, entry_point # no relocation needed
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nop
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reloc_loop:
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lw s0, 0(v0) # src
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lw s1, 4(v0)
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lw s2, 8(v0)
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lw s3, 12(v0)
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sw s0, 0(t0) # dst
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sw s1, 4(t0)
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sw s2, 8(t0)
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sw s3, 12(t0)
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synci 0(t0) # dcache writeback invalidate
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# icache invalidate
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addiu t0, t0, 16 # inc dst addr
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blt t0, t1, reloc_loop
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addiu v0, v0, 16 # inc src addr
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entry_point_jump:
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la t0, entry_point
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jr.hb t0
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nop
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entry_point:
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intc_setup:
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li t0, 0xb0020000 # INTC base
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lw zero, 4(t0) # INTC_MSK mask all interrupt sources
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core_irq_setup:
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li t0, 0x00404000 # BEV=1 for C0_EBASE setup, IM6=1, IE=0
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mtc0 t0, C0_STATUS
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la t0, _irqbase # vectors base address must be 4k aligned
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mtc0 t0, C0_EBASE
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li t0, 0x00004000
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mtc0 t0, C0_STATUS # BEV=0, IM6=1, IE=0
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li t1, 0x08800000
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mtc0 t1, C0_CAUSE # DC=1, IV=1
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mtc0 zero,C0_INTCTL # VS = 0
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# clear bss
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la t0, bssbegin
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la t1, bssend
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beq t0, t1, stack_setup
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nop
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clear_bss_loop:
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sw zero, 0(t0)
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bne t0, t1, clear_bss_loop
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addiu t0, 4
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stack_setup:
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# setup stack
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la k0, irqstackend
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la sp, stackend
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la t0, stackbegin
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li t1, 0xdeadbeef
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stack_munge_loop:
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sw t1, 0(t0)
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bne t0, sp, stack_munge_loop
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addiu t0, 4
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# jump to C code with enabled interrupts
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la t0, main
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jr.hb t0
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ei
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.set at
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.set reorder
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/* s0-s7 not saved as this are callee saved registers
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* CO_STATUS is not saved as nested interrupts are not supported
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*
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* Separate irqstack is used for context save and irq processing
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* k0 holds the address of the top of this stack and k1 is used
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* to hold original sp value. Since we do not support nesting
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* there is nothing to worry about
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*/
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.extern INT_UDC
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.global irq_handler
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.set mips32r2
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.set noreorder
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.set noat
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.section .irq_vector,"ax",%progbits
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irq_handler:
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move k1, sp
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move sp, k0
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addiu sp, sp, -84
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/* context save */
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sw AT, 0(sp)
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sw v0, 4(sp)
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sw v1, 8(sp)
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sw a0, 12(sp)
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sw a1, 16(sp)
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sw a2, 20(sp)
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sw a3, 24(sp)
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sw t0, 28(sp)
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sw t1, 32(sp)
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sw t2, 36(sp)
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sw t3, 40(sp)
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sw t4, 44(sp)
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sw t5, 48(sp)
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sw t6, 52(sp)
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sw t7, 56(sp)
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sw t8, 60(sp)
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sw t9, 64(sp)
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sw fp, 68(sp)
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sw ra, 72(sp)
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mfhi t0
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mflo t1
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sw t0, 76(sp)
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sw t1, 80(sp)
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/* handle interrupt */
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lui t0, 0xb002 /* INTC base */
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lw a0, 0(t0) /* INTC_PD */
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lw a1, 4(t0) /* INTC_MSK */
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and a0, a0, a1 /* mask */
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andi a0, a0, 0x10 /* UDC flag */
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beq a0, zero, restore
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nop
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/* irq dispatch */
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la a0, INT_UDC
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jalr a0
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nop
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restore:
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/* context restore */
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lw t0, 76(sp)
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lw t1, 80(sp)
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mthi t0
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mtlo t1
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lw AT, 0(sp)
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lw v0, 4(sp)
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lw v1, 8(sp)
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lw a0, 12(sp)
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lw a1, 16(sp)
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lw a2, 20(sp)
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lw a3, 24(sp)
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lw t0, 28(sp)
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lw t1, 32(sp)
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lw t2, 36(sp)
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lw t3, 40(sp)
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lw t4, 44(sp)
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lw t5, 48(sp)
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lw t6, 52(sp)
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lw t7, 56(sp)
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lw t8, 60(sp)
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lw t9, 64(sp)
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lw fp, 68(sp)
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lw ra, 72(sp)
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addiu sp, sp, 84
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move sp, k1
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eret
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.set reorder
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.set at
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