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.text
.balign 4
.global _start
_start:
seth sp, #shigh(_stack)
add3 sp, sp, #low(_stack)
ldi fp, #0
# Clear the BSS. Do it in two parts for efficiency: longwords first
# for most of it, then the remaining 0 to 3 bytes.
seth r2, #shigh(__bss_start)
add3 r2, r2, #low(__bss_start); R2 = start of BSS
seth r3, #shigh(_end)
add3 r3, r3, #low(_end) ; R3 = end of BSS + 1
sub r3, r2 ; R3 = BSS size in bytes
mv r4, r3
srli r4, #2 ; R4 = BSS size in longwords (rounded down)
ldi r1, #0 ; clear R1 for longword store
addi r2, #-4 ; account for pre-inc store
beqz r4, .Lendloop1 ; any more to go?
.Lloop1:
st r1, @+r2 ; yep, zero out another longword
addi r4, #-1 ; decrement count
bnez r4, .Lloop1 ; go do some more
.Lendloop1:
and3 r4, r3, #3 ; get no. of remaining BSS bytes to clear
addi r2, #4 ; account for pre-inc store
beqz r4, .Lendloop2 ; any more to go?
.Lloop2:
stb r1, @r2 ; yep, zero out another byte
addi r2, #1 ; bump address
addi r4, #-1 ; decrement count
bnez r4, .Lloop2 ; go do some more
.Lendloop2:
# Run code in the .init section.
# This will queue the .fini section to be run with atexit.
bl __init
# Call main, then exit.
bl main
bl exit
# If that fails just loop.
.Lexit:
bra .Lexit
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