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https://opencores.org/ocsvn/eco32/eco32/trunk
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[/] [eco32/] [trunk/] [stdalone/] [onetask/] [os/] [start.s] - Rev 152
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; ; start.s -- startup code ; .import main .import _ecode .import _edata .import _ebss .export _bcode .export _bdata .export _bbss .export enable .export disable .export getISR .export setISR .export startTask .export setTLB .code _bcode: .data _bdata: .bss _bbss: .code ; reset arrives here reset: j start ; interrupts arrive here intrpt: j isr ; user TLB misses arrive here userMiss: j userMiss isr: add $26,$29,$0 ; sp -> $26 add $27,$1,$0 ; $1 -> $27 add $29,$0,istack ; setup interrupt stack sub $29,$29,128 ; save registers stw $2,$29,8 stw $3,$29,12 stw $4,$29,16 stw $5,$29,20 stw $6,$29,24 stw $7,$29,28 stw $8,$29,32 stw $9,$29,36 stw $10,$29,40 stw $11,$29,44 stw $12,$29,48 stw $13,$29,52 stw $14,$29,56 stw $15,$29,60 stw $16,$29,64 stw $17,$29,68 stw $18,$29,72 stw $19,$29,76 stw $20,$29,80 stw $21,$29,84 stw $22,$29,88 stw $23,$29,92 stw $24,$29,96 stw $25,$29,100 stw $26,$29,116 ; this is the task's sp stw $27,$29,4 ; this is the task's $1 stw $30,$29,120 ; this is the task's resumption address stw $31,$29,124 add $5,$29,$0 ; $5 = pointer to register array mvfs $4,0 ; $4 = IRQ number slr $4,$4,16 and $4,$4,0x1F sll $26,$4,2 ; $26 = 4 * IRQ number ldw $26,$26,irqsrv ; get addr of service routine jalr $26 ; call service routine j resume ; resume interrupted task if ISR returns ; resume a task resume: ldw $2,$29,8 ; restore registers ldw $3,$29,12 ldw $4,$29,16 ldw $5,$29,20 ldw $6,$29,24 ldw $7,$29,28 ldw $8,$29,32 ldw $9,$29,36 ldw $10,$29,40 ldw $11,$29,44 ldw $12,$29,48 ldw $13,$29,52 ldw $14,$29,56 ldw $15,$29,60 ldw $16,$29,64 ldw $17,$29,68 ldw $18,$29,72 ldw $19,$29,76 ldw $20,$29,80 ldw $21,$29,84 ldw $22,$29,88 ldw $23,$29,92 ldw $24,$29,96 ldw $25,$29,100 ldw $26,$29,116 ; this is the task's sp ldw $27,$29,4 ; this is the task's $1 ldw $30,$29,120 ; this is the task's resumption address ldw $31,$29,124 add $1,$27,$0 ; $27 -> $1 add $29,$26,$0 ; $26 -> sp rfx ; return from exception start: add $8,$0,0xA8003FFF add $9,$0,0xC0000000 stw $8,$9,0 ; 0xC0000000: j 0xC0010000 stw $8,$9,4 ; 0xC0000004: j 0xC0010004 stw $8,$9,8 ; 0xC0000008: j 0xC0010008 mvfs $8,0 or $8,$8,1 << 27 ; let vector point to RAM mvts $8,0 add $29,$0,stack ; set sp add $10,$0,_bdata ; copy data segment add $8,$0,_edata sub $9,$8,$10 add $9,$9,_ecode j cpytest cpyloop: ldw $11,$9,0 stw $11,$8,0 cpytest: sub $8,$8,4 sub $9,$9,4 bgeu $8,$10,cpyloop add $8,$0,_bbss ; clear bss add $9,$0,_ebss j clrtest clrloop: stw $0,$8,0 add $8,$8,4 clrtest: bltu $8,$9,clrloop jal main ; call 'main' start1: j start1 ; loop enable: mvfs $8,0 or $8,$8,1 << 23 mvts $8,0 jr $31 disable: mvfs $8,0 and $8,$8,~(1 << 23) mvts $8,0 jr $31 getISR: sll $4,$4,2 ldw $2,$4,irqsrv jr $31 setISR: sll $4,$4,2 stw $5,$4,irqsrv jr $31 startTask: or $29,$4,0xC0000000 sub $29,$29,128 stw $0,$29,0 ; preset registers stw $0,$29,4 stw $0,$29,8 stw $0,$29,12 stw $0,$29,16 stw $0,$29,20 stw $0,$29,24 stw $0,$29,28 stw $0,$29,32 stw $0,$29,36 stw $0,$29,40 stw $0,$29,44 stw $0,$29,48 stw $0,$29,52 stw $0,$29,56 stw $0,$29,60 stw $0,$29,64 stw $0,$29,68 stw $0,$29,72 stw $0,$29,76 stw $0,$29,80 stw $0,$29,84 stw $0,$29,88 stw $0,$29,92 stw $0,$29,96 stw $0,$29,100 stw $0,$29,104 stw $0,$29,108 stw $0,$29,112 add $8,$0,0x80000000 stw $8,$29,116 ; sp stw $0,$29,120 ; task starts at virtual address 0 stw $0,$29,124 mvfs $8,0 or $8,$8,1 << 25 ; set previous mode to 'user' mvts $8,0 j resume setTLB: mvts $4,1 ; set index mvts $5,2 ; set entryHi mvts $6,3 ; set entryLo tbwi ; write TLB entry at index jr $31 .data ; interrupt service routine table .align 4 irqsrv: .word 0 ; 00: terminal 0 transmitter interrupt .word 0 ; 01: terminal 0 receiver interrupt .word 0 ; 02: terminal 1 transmitter interrupt .word 0 ; 03: terminal 1 receiver interrupt .word 0 ; 04: keyboard interrupt .word 0 ; 05: unused .word 0 ; 06: unused .word 0 ; 07: unused .word 0 ; 08: disk interrupt .word 0 ; 09: unused .word 0 ; 10: unused .word 0 ; 11: unused .word 0 ; 12: unused .word 0 ; 13: unused .word 0 ; 14: timer 0 interrupt .word 0 ; 15: timer 1 interrupt .word 0 ; 16: bus timeout exception .word 0 ; 17: illegal instruction exception .word 0 ; 18: privileged instruction exception .word 0 ; 19: divide instruction exception .word 0 ; 20: trap instruction exception .word 0 ; 21: TLB miss exception .word 0 ; 22: TLB write exception .word 0 ; 23: TLB invalid exception .word 0 ; 24: illegal address exception .word 0 ; 25: privileged address exception .word 0 ; 26: unused .word 0 ; 27: unused .word 0 ; 28: unused .word 0 ; 29: unused .word 0 ; 30: unused .word 0 ; 31: unused .bss .align 4 .space 0x800 stack: .align 4 .space 0x800 istack:
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