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.global main
.global isr
.section .text.start
.global _start
_start:
j crt_init
.section .text
.global trap_entry
trap_entry:
sw x1, - 1*4(sp)
sw x5, - 2*4(sp)
sw x6, - 3*4(sp)
sw x7, - 4*4(sp)
sw x10, - 5*4(sp)
sw x11, - 6*4(sp)
sw x12, - 7*4(sp)
sw x13, - 8*4(sp)
sw x14, - 9*4(sp)
sw x15, -10*4(sp)
sw x16, -11*4(sp)
sw x17, -12*4(sp)
sw x28, -13*4(sp)
sw x29, -14*4(sp)
sw x30, -15*4(sp)
sw x31, -16*4(sp)
addi sp,sp,-16*4
call isr
lw x1 , 15*4(sp)
lw x5, 14*4(sp)
lw x6, 13*4(sp)
lw x7, 12*4(sp)
lw x10, 11*4(sp)
lw x11, 10*4(sp)
lw x12, 9*4(sp)
lw x13, 8*4(sp)
lw x14, 7*4(sp)
lw x15, 6*4(sp)
lw x16, 5*4(sp)
lw x17, 4*4(sp)
lw x28, 3*4(sp)
lw x29, 2*4(sp)
lw x30, 1*4(sp)
lw x31, 0*4(sp)
addi sp,sp,16*4
mret
.text
crt_init:
la sp, _estack - 4
la a0, trap_entry
csrw mtvec, a0
bss_init:
la a0, _sbss
la a1, _ebss + 4
bss_loop:
beq a0,a1,bss_done
sw zero,0(a0)
add a0,a0,4
j bss_loop
bss_done:
/* Load DATA */
la t0, _etext
la t1, _srelocate
la t2, _erelocate + 4
3:
lw t3, 0(t0)
sw t3, 0(t1)
/* _edata is aligned to 4 bytes. Use word-xfers. */
addi t0, t0, 4
addi t1, t1, 4
bltu t1, t2, 3b
li a0, 0x880 //880 enable timer + external interrupt sources (until mstatus.MIE is set, they will never trigger an interrupt)
csrw mie,a0
call main
infinite_loop:
j infinite_loop
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