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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;
# create initial stack frame for new thread
clrrdi 4, 4, 4
li 0, 0
stdu 0,-32(4)
# save fn and arg to child stack
std 3, 8(4)
std 6, 16(4)
# shuffle args into correct registers and call SYS_clone
mr 3, 5
#mr 4, 4
mr 5, 7
mr 6, 8
mr 7, 9
li 0, 120 # SYS_clone = 120
sc
# if error, negate return (errno)
bns+ 1f
neg 3, 3
1: # if we're the parent, return
cmpwi cr7, 3, 0
bnelr cr7
# we're the child. call fn(arg)
ld 3, 16(1)
ld 12, 8(1)
mtctr 12
bctrl
# call SYS_exit. exit code is already in r3 from fn return value
li 0, 1 # SYS_exit = 1
sc
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