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TS = 0
TE = 1
FROM = 2
N = 3
TMP = 3 /* N and TMP don't overlap */
TMP1 = 4
TEXT memcpy(SB), $0
B _memmove
TEXT memmove(SB), $0
_memmove:
MOVW R(TS), to+0(FP) /* need to save for return value */
MOVW from+4(FP), R(FROM)
MOVW n+8(FP), R(N)
ADD R(N), R(TS), R(TE) /* to end pointer */
CMP R(FROM), R(TS)
BLS _forward
_back:
ADD R(N), R(FROM) /* from end pointer */
CMP $4, R(N) /* need at least 4 bytes to copy */
BLT _b1tail
_b4align: /* align destination on 4 */
AND.S $3, R(TE), R(TMP)
BEQ _b4aligned
MOVBU.W -1(R(FROM)), R(TMP) /* pre-indexed */
MOVBU.W R(TMP), -1(R(TE)) /* pre-indexed */
B _b4align
_b4aligned: /* is source now aligned? */
AND.S $3, R(FROM), R(TMP)
BNE _bunaligned
ADD $31, R(TS), R(TMP) /* do 32-byte chunks if possible */
_b32loop:
CMP R(TMP), R(TE)
BLS _b4tail
MOVM.DB.W (R(FROM)), [R4-R7]
MOVM.DB.W [R4-R7], (R(TE))
MOVM.DB.W (R(FROM)), [R4-R7]
MOVM.DB.W [R4-R7], (R(TE))
B _b32loop
_b4tail: /* do remaining words if possible */
ADD $3, R(TS), R(TMP)
_b4loop:
CMP R(TMP), R(TE)
BLS _b1tail
MOVW.W -4(R(FROM)), R(TMP1) /* pre-indexed */
MOVW.W R(TMP1), -4(R(TE)) /* pre-indexed */
B _b4loop
_b1tail: /* remaining bytes */
CMP R(TE), R(TS)
BEQ _return
MOVBU.W -1(R(FROM)), R(TMP) /* pre-indexed */
MOVBU.W R(TMP), -1(R(TE)) /* pre-indexed */
B _b1tail
_forward:
CMP $4, R(N) /* need at least 4 bytes to copy */
BLT _f1tail
_f4align: /* align destination on 4 */
AND.S $3, R(TS), R(TMP)
BEQ _f4aligned
MOVBU.P 1(R(FROM)), R(TMP) /* implicit write back */
MOVBU.P R(TMP), 1(R(TS)) /* implicit write back */
B _f4align
_f4aligned: /* is source now aligned? */
AND.S $3, R(FROM), R(TMP)
BNE _funaligned
SUB $31, R(TE), R(TMP) /* do 32-byte chunks if possible */
_f32loop:
CMP R(TMP), R(TS)
BHS _f4tail
MOVM.IA.W (R(FROM)), [R4-R7]
MOVM.IA.W [R4-R7], (R(TS))
MOVM.IA.W (R(FROM)), [R4-R7]
MOVM.IA.W [R4-R7], (R(TS))
B _f32loop
_f4tail:
SUB $3, R(TE), R(TMP) /* do remaining words if possible */
_f4loop:
CMP R(TMP), R(TS)
BHS _f1tail
MOVW.P 4(R(FROM)), R(TMP1) /* implicit write back */
MOVW.P R4, 4(R(TS)) /* implicit write back */
B _f4loop
_f1tail:
CMP R(TS), R(TE)
BEQ _return
MOVBU.P 1(R(FROM)), R(TMP) /* implicit write back */
MOVBU.P R(TMP), 1(R(TS)) /* implicit write back */
B _f1tail
_return:
MOVW to+0(FP), R0
RET
RSHIFT = 4
LSHIFT = 5
OFFSET = 11
BR0 = 6
BW0 = 7
BR1 = 7
BW1 = 8
_bunaligned:
CMP $2, R(TMP) /* is R(TMP) < 2 ? */
MOVW.LT $8, R(RSHIFT) /* (R(n)<<24)|(R(n-1)>>8) */
MOVW.LT $24, R(LSHIFT)
MOVW.LT $1, R(OFFSET)
MOVW.EQ $16, R(RSHIFT) /* (R(n)<<16)|(R(n-1)>>16) */
MOVW.EQ $16, R(LSHIFT)
MOVW.EQ $2, R(OFFSET)
MOVW.GT $24, R(RSHIFT) /* (R(n)<<8)|(R(n-1)>>24) */
MOVW.GT $8, R(LSHIFT)
MOVW.GT $3, R(OFFSET)
ADD $8, R(TS), R(TMP) /* do 8-byte chunks if possible */
CMP R(TMP), R(TE)
BLS _b1tail
BIC $3, R(FROM) /* align source */
MOVW (R(FROM)), R(BR0) /* prime first block register */
_bu8loop:
CMP R(TMP), R(TE)
BLS _bu1tail
MOVW R(BR0)<<R(LSHIFT), R(BW1)
MOVM.DB.W (R(FROM)), [R(BR0)-R(BR1)]
ORR R(BR1)>>R(RSHIFT), R(BW1)
MOVW R(BR1)<<R(LSHIFT), R(BW0)
ORR R(BR0)>>R(RSHIFT), R(BW0)
MOVM.DB.W [R(BW0)-R(BW1)], (R(TE))
B _bu8loop
_bu1tail:
ADD R(OFFSET), R(FROM)
B _b1tail
RSHIFT = 4
LSHIFT = 5
OFFSET = 11
FW0 = 6
FR0 = 7
FW1 = 7
FR1 = 8
_funaligned:
CMP $2, R(TMP)
MOVW.LT $8, R(RSHIFT) /* (R(n+1)<<24)|(R(n)>>8) */
MOVW.LT $24, R(LSHIFT)
MOVW.LT $3, R(OFFSET)
MOVW.EQ $16, R(RSHIFT) /* (R(n+1)<<16)|(R(n)>>16) */
MOVW.EQ $16, R(LSHIFT)
MOVW.EQ $2, R(OFFSET)
MOVW.GT $24, R(RSHIFT) /* (R(n+1)<<8)|(R(n)>>24) */
MOVW.GT $8, R(LSHIFT)
MOVW.GT $1, R(OFFSET)
SUB $8, R(TE), R(TMP) /* do 8-byte chunks if possible */
CMP R(TMP), R(TS)
BHS _f1tail
BIC $3, R(FROM) /* align source */
MOVW.P 4(R(FROM)), R(FR1) /* prime last block register, implicit write back */
_fu8loop:
CMP R(TMP), R(TS)
BHS _fu1tail
MOVW R(FR1)>>R(RSHIFT), R(FW0)
MOVM.IA.W (R(FROM)), [R(FR0)-R(FR1)]
ORR R(FR0)<<R(LSHIFT), R(FW0)
MOVW R(FR0)>>R(RSHIFT), R(FW1)
ORR R(FR1)<<R(LSHIFT), R(FW1)
MOVM.IA.W [R(FW0)-R(FW1)], (R(TS))
B _fu8loop
_fu1tail:
SUB R(OFFSET), R(FROM)
B _f1tail