Annotation of OpenXM_contrib/gmp/mpn/m68k/rshift.S, Revision 1.1
1.1 ! maekawa 1: /* mc68020 __mpn_rshift -- Shift right a low-level natural-number integer.
! 2:
! 3: Copyright (C) 1996 Free Software Foundation, Inc.
! 4:
! 5: This file is part of the GNU MP Library.
! 6:
! 7: The GNU MP Library is free software; you can redistribute it and/or modify
! 8: it under the terms of the GNU Library General Public License as published by
! 9: the Free Software Foundation; either version 2 of the License, or (at your
! 10: option) any later version.
! 11:
! 12: The GNU MP Library is distributed in the hope that it will be useful, but
! 13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
! 14: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
! 15: License for more details.
! 16:
! 17: You should have received a copy of the GNU Library General Public License
! 18: along with the GNU MP Library; see the file COPYING.LIB. If not, write to
! 19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
! 20: MA 02111-1307, USA. */
! 21:
! 22: /*
! 23: INPUT PARAMETERS
! 24: res_ptr (sp + 4)
! 25: s_ptr (sp + 8)
! 26: s_size (sp + 16)
! 27: cnt (sp + 12)
! 28: */
! 29:
! 30: #include "sysdep.h"
! 31: #include "asm-syntax.h"
! 32:
! 33: #define res_ptr a1
! 34: #define s_ptr a0
! 35: #define s_size d6
! 36: #define cnt d4
! 37:
! 38: TEXT
! 39: ALIGN
! 40: GLOBL C_SYMBOL_NAME(__mpn_rshift)
! 41:
! 42: C_SYMBOL_NAME(__mpn_rshift:)
! 43: PROLOG(__mpn_rshift)
! 44: /* Save used registers on the stack. */
! 45: moveml R(d2)-R(d6)/R(a2),MEM_PREDEC(sp)
! 46:
! 47: /* Copy the arguments to registers. */
! 48: movel MEM_DISP(sp,28),R(res_ptr)
! 49: movel MEM_DISP(sp,32),R(s_ptr)
! 50: movel MEM_DISP(sp,36),R(s_size)
! 51: movel MEM_DISP(sp,40),R(cnt)
! 52:
! 53: moveql #1,R(d5)
! 54: cmpl R(d5),R(cnt)
! 55: bne L(Lnormal)
! 56: cmpl R(res_ptr),R(s_ptr)
! 57: bls L(Lspecial) /* jump if res_ptr >= s_ptr */
! 58: #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
! 59: lea MEM_INDX1(res_ptr,s_size,l,4),R(a2)
! 60: #else /* not mc68020 */
! 61: movel R(s_size),R(d0)
! 62: asll #2,R(d0)
! 63: lea MEM_INDX(res_ptr,d0,l),R(a2)
! 64: #endif
! 65: cmpl R(s_ptr),R(a2)
! 66: bls L(Lspecial) /* jump if s_ptr >= res_ptr + s_size */
! 67:
! 68: L(Lnormal:)
! 69: moveql #32,R(d5)
! 70: subl R(cnt),R(d5)
! 71: movel MEM_POSTINC(s_ptr),R(d2)
! 72: movel R(d2),R(d0)
! 73: lsll R(d5),R(d0) /* compute carry limb */
! 74:
! 75: lsrl R(cnt),R(d2)
! 76: movel R(d2),R(d1)
! 77: subql #1,R(s_size)
! 78: beq L(Lend)
! 79: lsrl #1,R(s_size)
! 80: bcs L(L1)
! 81: subql #1,R(s_size)
! 82:
! 83: L(Loop:)
! 84: movel MEM_POSTINC(s_ptr),R(d2)
! 85: movel R(d2),R(d3)
! 86: lsll R(d5),R(d3)
! 87: orl R(d3),R(d1)
! 88: movel R(d1),MEM_POSTINC(res_ptr)
! 89: lsrl R(cnt),R(d2)
! 90: L(L1:)
! 91: movel MEM_POSTINC(s_ptr),R(d1)
! 92: movel R(d1),R(d3)
! 93: lsll R(d5),R(d3)
! 94: orl R(d3),R(d2)
! 95: movel R(d2),MEM_POSTINC(res_ptr)
! 96: lsrl R(cnt),R(d1)
! 97:
! 98: dbf R(s_size),L(Loop)
! 99: subl #0x10000,R(s_size)
! 100: bcc L(Loop)
! 101:
! 102: L(Lend:)
! 103: movel R(d1),MEM(res_ptr) /* store most significant limb */
! 104:
! 105: /* Restore used registers from stack frame. */
! 106: moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
! 107: rts
! 108:
! 109: /* We loop from most significant end of the arrays, which is only
! 110: permissable if the source and destination don't overlap, since the
! 111: function is documented to work for overlapping source and destination. */
! 112:
! 113: L(Lspecial:)
! 114: #if (defined (__mc68020__) || defined (__NeXT__) || defined(mc68020))
! 115: lea MEM_INDX1(s_ptr,s_size,l,4),R(s_ptr)
! 116: lea MEM_INDX1(res_ptr,s_size,l,4),R(res_ptr)
! 117: #else /* not mc68000 */
! 118: movel R(s_size),R(d0)
! 119: asll #2,R(d0)
! 120: addl R(s_size),R(s_ptr)
! 121: addl R(s_size),R(res_ptr)
! 122: #endif
! 123:
! 124: clrl R(d0) /* initialize carry */
! 125: eorw #1,R(s_size)
! 126: lsrl #1,R(s_size)
! 127: bcc L(LL1)
! 128: subql #1,R(s_size)
! 129:
! 130: L(LLoop:)
! 131: movel MEM_PREDEC(s_ptr),R(d2)
! 132: roxrl #1,R(d2)
! 133: movel R(d2),MEM_PREDEC(res_ptr)
! 134: L(LL1:)
! 135: movel MEM_PREDEC(s_ptr),R(d2)
! 136: roxrl #1,R(d2)
! 137: movel R(d2),MEM_PREDEC(res_ptr)
! 138:
! 139: dbf R(s_size),L(LLoop)
! 140: roxrl #1,R(d0) /* save cy in msb */
! 141: subl #0x10000,R(s_size)
! 142: bcs L(LLend)
! 143: addl R(d0),R(d0) /* restore cy */
! 144: bra L(LLoop)
! 145:
! 146: L(LLend:)
! 147: /* Restore used registers from stack frame. */
! 148: moveml MEM_POSTINC(sp),R(d2)-R(d6)/R(a2)
! 149: rts
! 150: EPILOG(__mpn_rshift)
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