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Diffstat (limited to 'mpi/m68k/mpih-rshift.S')
| -rw-r--r-- | mpi/m68k/mpih-rshift.S | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/mpi/m68k/mpih-rshift.S b/mpi/m68k/mpih-rshift.S new file mode 100644 index 000000000..5670888c9 --- /dev/null +++ b/mpi/m68k/mpih-rshift.S @@ -0,0 +1,156 @@ +/* mc68020 rshift -- Shift right a low-level natural-number integer. + +Copyright (C) 1996, 1998 Free Software Foundation, Inc. + +This file is part of GNUPG. + +GNUPG is free software; you can redistribute it and/or modify +it under the terms of the GNU Library General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at your +option) any later version. + +GNUPG is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public +License for more details. + +You should have received a copy of the GNU Library General Public License +along with the GNU MP Library; see the file COPYING.LIB. If not, write to +the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, +MA 02111-1307, USA. +*/ + +#include "sysdep.h" +#include "asm-syntax.h" + + +/******************* + * mpi_limb_t + * mpihelp_rshift( mpi_ptr_t wp, (sp + 4) + * mpi_ptr_t up, (sp + 8) + * mpi_size_t usize, (sp + 12) + * unsigned cnt) (sp + 16) + */ + +#define res_ptr a1 +#define s_ptr a0 +#define s_size d6 +#define cnt d4 + + TEXT + ALIGN + GLOBL C_SYMBOL_NAME(mpihelp_rshift) + +C_SYMBOL_NAME(mpihelp_rshift:) +PROLOG(mpihelp_rshift) + /* Save used registers on the stack. */ + moveml R(d2)-R(d6)/R(a2),MEM_PREDEC(sp) + + /* Copy the arguments to registers. */ + movel MEM_DISP(sp,28),R(res_ptr) + movel MEM_DISP(sp,32),R(s_ptr) + movel MEM_DISP(sp,36),R(s_size) + movel MEM_DISP(sp,40),R(cnt) + + moveql #1,R(d5) + cmpl R(d5),R(cnt) + bne L(Rnormal) + cmpl R(res_ptr),R(s_ptr) + bls L(Rspecial) /* jump if res_ptr >= s_ptr */ +#if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020)) + lea MEM_INDX1(res_ptr,s_size,l,4),R(a2) +#else /* not mc68020 */ + movel R(s_size),R(d0) + asll #2,R(d0) + lea MEM_INDX(res_ptr,d0,l),R(a2) +#endif + cmpl R(s_ptr),R(a2) + bls L(Rspecial) /* jump if s_ptr >= res_ptr + s_size */ + +L(Rnormal:) + moveql #32,R(d5) + subl R(cnt),R(d5) + movel MEM_POSTINC(s_ptr),R(d2) + movel R(d2),R(d0) + lsll R(d5),R(d0) /* compute carry limb */ + + lsrl R(cnt),R(d2) + movel R(d2),R(d1) + subql #1,R(s_size) + beq L(Rend) + lsrl #1,R(s_size) + bcs L(R1) + subql #1,R(s_size) + +L(Roop:) + movel MEM_POSTINC(s_ptr),R(d2) + movel R(d2),R(d3) + lsll R(d5),R(d3) + orl R(d3),R(d1) + movel R(d1),MEM_POSTINC(res_ptr) + lsrl R(cnt),R(d2) +L(R1:) + movel MEM_POSTINC(s_ptr),R(d1) + movel R(d1),R(d3) + lsll R(d5),R(d3) + orl R(d3),R(d2) + movel R(d2),MEM_POSTINC(res_ptr) + lsrl R(cnt),R(d1) + + dbf R(s_size),L(Roop) + subl #0x10000,R(s_size) + bcc L(Roop) + +L(Rend:) + movel R(d1),MEM(res_ptr) /* store most significant limb */ + +/* Restore used registers from stack frame. */ + moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2) + rts + +/* We loop from most significant end of the arrays, which is only + permissable if the source and destination don't overlap, since the + function is documented to work for overlapping source and destination. */ + +L(Rspecial:) +#if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020)) + lea MEM_INDX1(s_ptr,s_size,l,4),R(s_ptr) + lea MEM_INDX1(res_ptr,s_size,l,4),R(res_ptr) +#else /* not mc68000 */ + movel R(s_size),R(d0) + asll #2,R(d0) + addl R(s_size),R(s_ptr) + addl R(s_size),R(res_ptr) +#endif + + clrl R(d0) /* initialize carry */ + eorw #1,R(s_size) + lsrl #1,R(s_size) + bcc L(LR1) + subql #1,R(s_size) + +L(LRoop:) + movel MEM_PREDEC(s_ptr),R(d2) + roxrl #1,R(d2) + movel R(d2),MEM_PREDEC(res_ptr) +L(LR1:) + movel MEM_PREDEC(s_ptr),R(d2) + roxrl #1,R(d2) + movel R(d2),MEM_PREDEC(res_ptr) + + dbf R(s_size),L(LRoop) + roxrl #1,R(d0) /* save cy in msb */ + subl #0x10000,R(s_size) + bcs L(LRend) + addl R(d0),R(d0) /* restore cy */ + bra L(LRoop) + +L(LRend:) +/* Restore used registers from stack frame. */ + moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2) + rts +EPILOG(mpihelp_rshift) + + + + |