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| | .text
.global __clone
.type __clone, %function
__clone:
# int clone(fn, stack, flags, arg, ptid, tls, ctid)
# a b c d e f g
# 3 4 5 6 7 8 9
# pseudo C code:
# tid = syscall(SYS_clone,c,b,e,f,g);
# if (!tid) syscall(SYS_exit, a(d));
# return tid;
# SYS_clone = 120
# SYS_exit = 1
# create initial stack frame for new thread
clrrwi 4, 4, 4
li 0, 0
stwu 0, -16(4)
# save fn and arg to child stack
stw 3, 4(4)
stw 6, 8(4)
#move c into first arg
mr 3, 5
#mr 4, 4
mr 5, 7
mr 6, 8
mr 7, 9
# move syscall number into r0
li 0, 120
sc
# check for syscall error
bns+ 1f # jump to label 1 if no summary overflow.
#else
neg 3, 3 #negate the result (errno)
1:
# compare sc result with 0
cmpwi cr7, 3, 0
# if not 0, return
bnelr cr7
#else: we're the child
#call funcptr: move arg (d) into r3
lwz 3, 8(1)
#load funcptr (a) into CTR
lwz 0, 4(1)
mtctr 0
# call CTR reg
bctrl
# mov SYS_exit into r0 (the exit param is already in r3)
li 0, 1
sc
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