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dnl mc68020 mpn_lshift -- mpn left shift.
dnl Copyright 1996, 1999-2003 Free Software Foundation, Inc.
dnl This file is part of the GNU MP Library.
dnl
dnl The GNU MP Library is free software; you can redistribute it and/or modify
dnl it under the terms of either:
dnl
dnl * the GNU Lesser General Public License as published by the Free
dnl Software Foundation; either version 3 of the License, or (at your
dnl option) any later version.
dnl
dnl or
dnl
dnl * the GNU General Public License as published by the Free Software
dnl Foundation; either version 2 of the License, or (at your option) any
dnl later version.
dnl
dnl or both in parallel, as here.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
dnl for more details.
dnl
dnl You should have received copies of the GNU General Public License and the
dnl GNU Lesser General Public License along with the GNU MP Library. If not,
dnl see https://www.gnu.org/licenses/.
include(`../config.m4')
C cycles/limb
C shift==1 shift>1
C 68040: 5 12
C mp_limb_t mpn_lshift (mp_ptr res_ptr, mp_srcptr s_ptr, mp_size_t s_size,
C unsigned cnt);
C
C The "cnt" parameter is either 16 bits or 32 bits depending on
C SIZEOF_UNSIGNED (see ABI notes in mpn/m68k/README). The value is of
C course only 1 to 31. When loaded as 16 bits there's garbage in the upper
C half, hence the use of cmpw. The shift instructions take the their count
C modulo 64, so the upper part doesn't matter to them either.
C
C INPUT PARAMETERS
C res_ptr (sp + 4)
C s_ptr (sp + 8)
C s_size (sp + 12)
C cnt (sp + 16)
define(res_ptr, `a1')
define(s_ptr, `a0')
define(s_size, `d6')
define(cnt, `d4')
ifdef(`SIZEOF_UNSIGNED',,
`m4_error(`SIZEOF_UNSIGNED not defined, should be in config.m4
')')
PROLOGUE(mpn_lshift)
C Save used registers on the stack.
moveml d2-d6/a2, M(-,sp)
C Copy the arguments to registers.
movel M(sp,28), res_ptr
movel M(sp,32), s_ptr
movel M(sp,36), s_size
ifelse(SIZEOF_UNSIGNED,2,
` movew M(sp,40), cnt',
` movel M(sp,40), cnt')
moveql #1, d5
cmpw d5, cnt
bne L(Lnormal)
cmpl s_ptr, res_ptr
bls L(Lspecial) C jump if s_ptr >= res_ptr
ifelse(scale_available_p,1,`
lea M(s_ptr,s_size,l,4), a2
',`
movel s_size, d0
asll #2, d0
lea M(s_ptr,d0,l), a2
')
cmpl res_ptr, a2
bls L(Lspecial) C jump if res_ptr >= s_ptr + s_size
L(Lnormal):
moveql #32, d5
subl cnt, d5
ifelse(scale_available_p,1,`
lea M(s_ptr,s_size,l,4), s_ptr
lea M(res_ptr,s_size,l,4), res_ptr
',`
movel s_size, d0
asll #2, d0
addl d0, s_ptr
addl d0, res_ptr
')
movel M(-,s_ptr), d2
movel d2, d0
lsrl d5, d0 C compute carry limb
lsll cnt, d2
movel d2, d1
subql #1, s_size
beq L(Lend)
lsrl #1, s_size
bcs L(L1)
subql #1, s_size
L(Loop):
movel M(-,s_ptr), d2
movel d2, d3
lsrl d5, d3
orl d3, d1
movel d1, M(-,res_ptr)
lsll cnt, d2
L(L1):
movel M(-,s_ptr), d1
movel d1, d3
lsrl d5, d3
orl d3, d2
movel d2, M(-,res_ptr)
lsll cnt, d1
dbf s_size, L(Loop)
subl #0x10000, s_size
bcc L(Loop)
L(Lend):
movel d1, M(-,res_ptr) C store least significant limb
C Restore used registers from stack frame.
moveml M(sp,+), d2-d6/a2
rts
C We loop from least significant end of the arrays, which is only
C permissable if the source and destination don't overlap, since the
C function is documented to work for overlapping source and destination.
L(Lspecial):
clrl d0 C initialize carry
eorw #1, s_size
lsrl #1, s_size
bcc L(LL1)
subql #1, s_size
L(LLoop):
movel M(s_ptr,+), d2
addxl d2, d2
movel d2, M(res_ptr,+)
L(LL1):
movel M(s_ptr,+), d2
addxl d2, d2
movel d2, M(res_ptr,+)
dbf s_size, L(LLoop)
addxl d0, d0 C save cy in lsb
subl #0x10000, s_size
bcs L(LLend)
lsrl #1, d0 C restore cy
bra L(LLoop)
L(LLend):
C Restore used registers from stack frame.
moveml M(sp,+), d2-d6/a2
rts
EPILOGUE(mpn_lshift)
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