smovecr.s

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

//
//      $Id: smovecr.S,v 1.1 1998/12/14 23:15:28 joel Exp $
//
//	smovecr.sa 3.1 12/10/90
//
//	The entry point sMOVECR returns the constant at the
//	offset given in the instruction field.
//
//	Input: An offset in the instruction word.
//
//	Output:	The constant rounded to the user's rounding
//		mode unchecked for overflow.
//
//	Modified: fp0.
//
//
//		Copyright (C) Motorola, Inc. 1990
//			All Rights Reserved
//
//	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA 
//	The copyright notice above does not evidence any  
//	actual or intended publication of such source code.

//SMOVECR	idnt	2,1 | Motorola 040 Floating Point Software Package

	|section 8

#include "fpsp.defs"

	|xref	nrm_set
	|xref	round
	|xref	PIRN
	|xref	PIRZRM
	|xref	PIRP
	|xref	SMALRN
	|xref	SMALRZRM
	|xref	SMALRP
	|xref	BIGRN
	|xref	BIGRZRM
	|xref	BIGRP

FZERO:	.long	00000000
//
//	FMOVECR 
//
	.global	smovcr
smovcr:
	bfextu	CMDREG1B(%a6){#9:#7},%d0 //get offset
	bfextu	USER_FPCR(%a6){#26:#2},%d1 //get rmode
//
// check range of offset
//
	tstb	%d0		//if zero, offset is to pi
	beqs	PI_TBL		//it is pi
	cmpib	#0x0a,%d0		//check range $01 - $0a
	bles	Z_VAL		//if in this range, return zero
	cmpib	#0x0e,%d0		//check range $0b - $0e
	bles	SM_TBL		//valid constants in this range
	cmpib	#0x2f,%d0		//check range $10 - $2f
	bles	Z_VAL		//if in this range, return zero 
	cmpib	#0x3f,%d0		//check range $30 - $3f
	ble  	BG_TBL		//valid constants in this range
Z_VAL:
	fmoves	FZERO,%fp0
	rts
PI_TBL:
	tstb	%d1		//offset is zero, check for rmode
	beqs	PI_RN		//if zero, rn mode
	cmpib	#0x3,%d1		//check for rp
	beqs	PI_RP		//if 3, rp mode
PI_RZRM:
	leal	PIRZRM,%a0	//rmode is rz or rm, load PIRZRM in a0
	bra	set_finx
PI_RN:
	leal	PIRN,%a0		//rmode is rn, load PIRN in a0
	bra	set_finx
PI_RP:
	leal	PIRP,%a0		//rmode is rp, load PIRP in a0
	bra	set_finx
SM_TBL:
	subil	#0xb,%d0		//make offset in 0 - 4 range
	tstb	%d1		//check for rmode
	beqs	SM_RN		//if zero, rn mode
	cmpib	#0x3,%d1		//check for rp
	beqs	SM_RP		//if 3, rp mode
SM_RZRM:
	leal	SMALRZRM,%a0	//rmode is rz or rm, load SMRZRM in a0
	cmpib	#0x2,%d0		//check if result is inex
	ble	set_finx	//if 0 - 2, it is inexact
	bra	no_finx		//if 3, it is exact
SM_RN:
	leal	SMALRN,%a0	//rmode is rn, load SMRN in a0
	cmpib	#0x2,%d0		//check if result is inex
	ble	set_finx	//if 0 - 2, it is inexact
	bra	no_finx		//if 3, it is exact
SM_RP:
	leal	SMALRP,%a0	//rmode is rp, load SMRP in a0
	cmpib	#0x2,%d0		//check if result is inex
	ble	set_finx	//if 0 - 2, it is inexact
	bra	no_finx		//if 3, it is exact
BG_TBL:
	subil	#0x30,%d0		//make offset in 0 - f range
	tstb	%d1		//check for rmode
	beqs	BG_RN		//if zero, rn mode
	cmpib	#0x3,%d1		//check for rp
	beqs	BG_RP		//if 3, rp mode
BG_RZRM:
	leal	BIGRZRM,%a0	//rmode is rz or rm, load BGRZRM in a0
	cmpib	#0x1,%d0		//check if result is inex
	ble	set_finx	//if 0 - 1, it is inexact
	cmpib	#0x7,%d0		//second check
	ble	no_finx		//if 0 - 7, it is exact
	bra	set_finx	//if 8 - f, it is inexact
BG_RN:
	leal	BIGRN,%a0	//rmode is rn, load BGRN in a0
	cmpib	#0x1,%d0		//check if result is inex
	ble	set_finx	//if 0 - 1, it is inexact
	cmpib	#0x7,%d0		//second check
	ble	no_finx		//if 0 - 7, it is exact
	bra	set_finx	//if 8 - f, it is inexact
BG_RP:
	leal	BIGRP,%a0	//rmode is rp, load SMRP in a0
	cmpib	#0x1,%d0		//check if result is inex
	ble	set_finx	//if 0 - 1, it is inexact
	cmpib	#0x7,%d0		//second check
	ble	no_finx		//if 0 - 7, it is exact
//	bra	set_finx	;if 8 - f, it is inexact
set_finx:
	orl	#inx2a_mask,USER_FPSR(%a6) //set inex2/ainex
no_finx:
	mulul	#12,%d0			//use offset to point into tables
	movel	%d1,L_SCR1(%a6)		//load mode for round call
	bfextu	USER_FPCR(%a6){#24:#2},%d1	//get precision
	tstl	%d1			//check if extended precision
//
// Precision is extended
//
	bnes	not_ext			//if extended, do not call round
	fmovemx (%a0,%d0),%fp0-%fp0		//return result in fp0
	rts
//
// Precision is single or double
//
not_ext:
	swap	%d1			//rnd prec in upper word of d1
	addl	L_SCR1(%a6),%d1		//merge rmode in low word of d1
	movel	(%a0,%d0),FP_SCR1(%a6)	//load first word to temp storage
	movel	4(%a0,%d0),FP_SCR1+4(%a6)	//load second word
	movel	8(%a0,%d0),FP_SCR1+8(%a6)	//load third word
	clrl	%d0			//clear g,r,s
	lea	FP_SCR1(%a6),%a0
	btstb	#sign_bit,LOCAL_EX(%a0)
	sne	LOCAL_SGN(%a0)		//convert to internal ext. format
	
	bsr	round			//go round the mantissa

	bfclr	LOCAL_SGN(%a0){#0:#8}	//convert back to IEEE ext format
	beqs	fin_fcr
	bsetb	#sign_bit,LOCAL_EX(%a0)
fin_fcr:
	fmovemx (%a0),%fp0-%fp0
	rts

	|end