Annotation of sys/arch/hppa/spmath/divu.S, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: divu.S,v 1.10 2005/01/23 18:01:30 mickey Exp $ */
! 2: /*
! 3: (c) Copyright 1986 HEWLETT-PACKARD COMPANY
! 4: To anyone who acknowledges that this file is provided "AS IS"
! 5: without any express or implied warranty:
! 6: permission to use, copy, modify, and distribute this file
! 7: for any purpose is hereby granted without fee, provided that
! 8: the above copyright notice and this notice appears in all
! 9: copies, and that the name of Hewlett-Packard Company not be
! 10: used in advertising or publicity pertaining to distribution
! 11: of the software without specific, written prior permission.
! 12: Hewlett-Packard Company makes no representations about the
! 13: suitability of this software for any purpose.
! 14: */
! 15: /* @(#)divu.s: Revision: 1.11.88.1 Date: 93/12/07 15:06:01 */
! 16:
! 17: #include <machine/asm.h>
! 18: #define _LOCORE
! 19: #include <machine/frame.h>
! 20:
! 21: ;************************************************************************
! 22: ; Implement an integer divide routine for 32-bit operands and 32-bit quotient
! 23: ; and remainder with operand values of zero (divisor only) treated specially.
! 24: ;
! 25: ;****************************************************************************
! 26: ; Definitions
! 27: ;****************************************************************************
! 28: ;
! 29: ; General registers
! 30: ;
! 31: gr0 .reg %r0 ; General register zero
! 32: rem .reg %r3 ; remainder and upper part of dividend
! 33: quo .reg %r4 ; quotient and lower part of dividend
! 34: dvr .reg %r5 ; divisor
! 35: tp .reg %r6 ; temp. reg.
! 36:
! 37: ;******************************************************************************
! 38: .text
! 39: LEAF_ENTRY(divu)
! 40: stws,ma rem,4(sp) ; save registers on stack
! 41: stws,ma quo,4(sp) ; save registers on stack
! 42: stws,ma dvr,4(sp) ; save registers on stack
! 43: stws,ma tp,4(sp) ; save registers on stack
! 44:
! 45: addi 0,arg2,dvr ; get divisor
! 46: addi 0,arg1,quo ; get lower dividend
! 47: addi 0,arg0,rem ; get upper dividend
! 48:
! 49: comib,>,n 0,dvr,hibit ; check for dvr >= 2**31
! 50: addi -1,gr0,tp ; set V-bit to 1
! 51: ds 0,tp,0
! 52: add quo,quo,quo ; shift msb bit into carry
! 53: ds rem,dvr,rem ; 1st divide step, if carry
! 54: ; out, msb of quotient = 0
! 55: addc quo,quo,quo ; shift quo with/into carry
! 56: ds rem,dvr,rem ; 2nd divide step
! 57: addc quo,quo,quo ; shift quo with/into carry
! 58: ds rem,dvr,rem ; 3rd divide step
! 59: addc quo,quo,quo ; shift quo with/into carry
! 60: ds rem,dvr,rem ; 4th divide step
! 61: addc quo,quo,quo ; shift quo with/into carry
! 62: ds rem,dvr,rem ; 5th divide step
! 63: addc quo,quo,quo ; shift quo with/into carry
! 64: ds rem,dvr,rem ; 6th divide step
! 65: addc quo,quo,quo ; shift quo with/into carry
! 66: ds rem,dvr,rem ; 7th divide step
! 67: addc quo,quo,quo ; shift quo with/into carry
! 68: ds rem,dvr,rem ; 8th divide step
! 69: addc quo,quo,quo ; shift quo with/into carry
! 70: ds rem,dvr,rem ; 9th divide step
! 71: addc quo,quo,quo ; shift quo with/into carry
! 72: ds rem,dvr,rem ; 10th divide step
! 73: addc quo,quo,quo ; shift quo with/into carry
! 74: ds rem,dvr,rem ; 11th divide step
! 75: addc quo,quo,quo ; shift quo with/into carry
! 76: ds rem,dvr,rem ; 12th divide step
! 77: addc quo,quo,quo ; shift quo with/into carry
! 78: ds rem,dvr,rem ; 13th divide step
! 79: addc quo,quo,quo ; shift quo with/into carry
! 80: ds rem,dvr,rem ; 14th divide step
! 81: addc quo,quo,quo ; shift quo with/into carry
! 82: ds rem,dvr,rem ; 15th divide step
! 83: addc quo,quo,quo ; shift quo with/into carry
! 84: ds rem,dvr,rem ; 16th divide step
! 85: addc quo,quo,quo ; shift quo with/into carry
! 86: ds rem,dvr,rem ; 17th divide step
! 87: addc quo,quo,quo ; shift quo with/into carry
! 88: ds rem,dvr,rem ; 18th divide step
! 89: addc quo,quo,quo ; shift quo with/into carry
! 90: ds rem,dvr,rem ; 19th divide step
! 91: addc quo,quo,quo ; shift quo with/into carry
! 92: ds rem,dvr,rem ; 20th divide step
! 93: addc quo,quo,quo ; shift quo with/into carry
! 94: ds rem,dvr,rem ; 21st divide step
! 95: addc quo,quo,quo ; shift quo with/into carry
! 96: ds rem,dvr,rem ; 22nd divide step
! 97: addc quo,quo,quo ; shift quo with/into carry
! 98: ds rem,dvr,rem ; 23rd divide step
! 99: addc quo,quo,quo ; shift quo with/into carry
! 100: ds rem,dvr,rem ; 24th divide step
! 101: addc quo,quo,quo ; shift quo with/into carry
! 102: ds rem,dvr,rem ; 25th divide step
! 103: addc quo,quo,quo ; shift quo with/into carry
! 104: ds rem,dvr,rem ; 26th divide step
! 105: addc quo,quo,quo ; shift quo with/into carry
! 106: ds rem,dvr,rem ; 27th divide step
! 107: addc quo,quo,quo ; shift quo with/into carry
! 108: ds rem,dvr,rem ; 28th divide step
! 109: addc quo,quo,quo ; shift quo with/into carry
! 110: ds rem,dvr,rem ; 29th divide step
! 111: addc quo,quo,quo ; shift quo with/into carry
! 112: ds rem,dvr,rem ; 30th divide step
! 113: addc quo,quo,quo ; shift quo with/into carry
! 114: ds rem,dvr,rem ; 31st divide step
! 115: addc quo,quo,quo ; shift quo with/into carry
! 116: ds rem,dvr,rem ; 32nd divide step,
! 117: addc quo,quo,quo ; shift last quo bit into quo
! 118: addb,>=,n rem,0,finish ; branch if pos. rem
! 119: add,< dvr,0,0 ; if dvr > 0, add dvr
! 120: add,tr rem,dvr,rem ; for correcting rem.
! 121: sub rem,dvr,rem ; else subtract dvr
! 122: ;
! 123: ; end of divide routine
! 124: ;
! 125: finish stws rem,0(arg3) ; save remainder in high part
! 126: ; of result
! 127: stws quo,4(arg3) ; save quotient in low part
! 128: ; of result
! 129: ldws,mb -4(sp),tp ; restore registers
! 130: ldws,mb -4(sp),dvr ; restore registers
! 131: ldws,mb -4(sp),quo ; restore registers
! 132: bv 0(rp) ; return
! 133: ldws,mb -4(sp),rem ; restore registers
! 134: ;
! 135: hibit ldo 32(0),tp ; initialize loop counter
! 136: add quo,quo,quo ; shift high bit into carry
! 137: loop addc rem,rem,rem ; shift in high bit of dvdl
! 138: addc,<> 0,0,0 ; if bit shifted out of dvdu,
! 139: ; want to do subtract
! 140: comb,<<,n rem,dvr,nosub ; if upper dividend > dvr,
! 141: sub rem,dvr,rem ; subtract and
! 142: add,tr dvr,dvr,0 ; set carry
! 143: nosub addi 0,0,0 ; otherwise clear carry
! 144: addib,> -1,tp,loop ; inc. counter; finished?
! 145: addc quo,quo,quo ; shift bit of result into dvdl
! 146: b finish+4 ; finish up
! 147: stws rem,0(arg3) ; save remainder in high part
! 148: ; of result
! 149: EXIT(divu)
! 150:
! 151: .end
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