Joppe Blondel
838204653a
TODO: think of other way of shifting in data. Bit errors make uploading difficult
100 lines
2.0 KiB
ArmAsm
100 lines
2.0 KiB
ArmAsm
.section .text.init
|
|
.globl _start
|
|
.type _start, @function
|
|
_start:
|
|
la sp, __stack_top
|
|
|
|
# Zero .bss
|
|
la t0, __bss_start
|
|
la t1, __bss_end
|
|
1:
|
|
bgeu t0, t1, 2f
|
|
sw zero, 0(t0)
|
|
addi t0, t0, 4
|
|
j 1b
|
|
|
|
2:
|
|
call main
|
|
|
|
3:
|
|
j 3b
|
|
|
|
.size _start, .-_start
|
|
|
|
|
|
.section .text
|
|
.globl trap_entry
|
|
.type trap_entry, @function
|
|
trap_entry:
|
|
# Save full integer context (except x0/x2) because an interrupt can
|
|
# preempt code with live values in any register, not just caller-saved.
|
|
addi sp, sp, -128
|
|
sw ra, 124(sp)
|
|
sw gp, 120(sp)
|
|
sw tp, 116(sp)
|
|
sw t0, 112(sp)
|
|
sw t1, 108(sp)
|
|
sw t2, 104(sp)
|
|
sw s0, 100(sp)
|
|
sw s1, 96(sp)
|
|
sw a0, 92(sp)
|
|
sw a1, 88(sp)
|
|
sw a2, 84(sp)
|
|
sw a3, 80(sp)
|
|
sw a4, 76(sp)
|
|
sw a5, 72(sp)
|
|
sw a6, 68(sp)
|
|
sw a7, 64(sp)
|
|
sw s2, 60(sp)
|
|
sw s3, 56(sp)
|
|
sw s4, 52(sp)
|
|
sw s5, 48(sp)
|
|
sw s6, 44(sp)
|
|
sw s7, 40(sp)
|
|
sw s8, 36(sp)
|
|
sw s9, 32(sp)
|
|
sw s10, 28(sp)
|
|
sw s11, 24(sp)
|
|
sw t3, 20(sp)
|
|
sw t4, 16(sp)
|
|
sw t5, 12(sp)
|
|
sw t6, 8(sp)
|
|
|
|
csrr t0, mcause
|
|
li t1, 0x80000007 # machine timer interrupt (RV32)
|
|
bne t0, t1, 1f
|
|
call timer_isr # C function that ACKs/clears the timer so i_timer_irq goes low
|
|
1:
|
|
lw t6, 8(sp)
|
|
lw t5, 12(sp)
|
|
lw t4, 16(sp)
|
|
lw t3, 20(sp)
|
|
lw s11, 24(sp)
|
|
lw s10, 28(sp)
|
|
lw s9, 32(sp)
|
|
lw s8, 36(sp)
|
|
lw s7, 40(sp)
|
|
lw s6, 44(sp)
|
|
lw s5, 48(sp)
|
|
lw s4, 52(sp)
|
|
lw s3, 56(sp)
|
|
lw s2, 60(sp)
|
|
lw a7, 64(sp)
|
|
lw a6, 68(sp)
|
|
lw a5, 72(sp)
|
|
lw a4, 76(sp)
|
|
lw a3, 80(sp)
|
|
lw a2, 84(sp)
|
|
lw a1, 88(sp)
|
|
lw a0, 92(sp)
|
|
lw s1, 96(sp)
|
|
lw s0, 100(sp)
|
|
lw t2, 104(sp)
|
|
lw t1, 108(sp)
|
|
lw t0, 112(sp)
|
|
lw tp, 116(sp)
|
|
lw gp, 120(sp)
|
|
lw ra, 124(sp)
|
|
addi sp, sp, 128
|
|
mret
|