/* scale.s - Motorola 68040 FP scaling routines (EXC) *//* Copyright 1991-1993 Wind River Systems, Inc. */	.data	.globl	_copyright_wind_river	.long	_copyright_wind_river/*modification history--------------------01f,21jul93,kdl  added .text (SPR #2372).01e,23aug92,jcf  changed bxxx to jxx.01d,26may92,rrr  the tree shuffle01c,10jan92,kdl  added modification history; general cleanup.01b,30dec91,kdl  put in changes from Motorola v3.3 (FPSP v2.1):	 	 clear the exceptional operand for zero underflow.01a,15aug91,kdl  original version, from Motorola FPSP v2.0.*//*DESCRIPTION	scalesa 3.2 2/18/91	The entry point sSCALE computes the destination operand	scaled by the source operand.  If the absoulute value of	the source operand is (>= 2^14) an overflow or underflow	is returned.	The entry point __x_sscale is called from __x_do_func to emulate	the fscale unimplemented instruction.	Input: Double-extended destination operand in FPTEMP,		double-extended source operand in ETEMP.	Output: The function returns scale(X,Y) to fp0.	Modifies: fp0.	Algorithm:		Copyright (C) Motorola, Inc. 1990			All Rights Reserved	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA	The copyright notice above does not evidence any	actual or intended publication of such source code.SCALE    idnt    2,1 Motorola 040 Floating Point Software Package	section	8NOMANUAL*/#include "fpsp040E.h"|	xref	__x_t_ovfl2|	xref	__x_t_unfl|	xref	__x_round|	xref	__x_t_resdnrmSRC_BNDS: .word	0x3fff,0x400c|| This entry point is used by the unimplemented instruction exception| handler.||||	FSCALE|	.text	.globl	__x_sscale__x_sscale:	fmovel		#0,fpcr		| clr user enabled exc	clrl		d1	movew		a6@(FPTEMP),d1	| get dest exponent	smi		a6@(L_SCR1)	| use L_SCR1 to hold sign	andil		#0x7fff,d1	| strip sign	movew		a6@(ETEMP),d0	| check src bounds	andiw		#0x7fff,d0	| clr sign bit	cmp2w		SRC_BNDS,d0	jcc 		src_in	cmpiw		#0x400c,d0	| test for too large	jge 		src_out|| The source input is below 1, so we check for denormalized numbers| and set unfl.|src_small:	moveb		a6@(DTAG),d0	andib		#0xe0,d0	tstb		d0	jeq 		no_denorm	st		a6@(STORE_FLG)	| dest already contains result	orl		#__x_unfl_mask,a6@(USER_FPSR) | set UNFLden_done:	lea		a6@(FPTEMP),a0	jra 		__x_t_resdnrmno_denorm:	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	| simply return dest	rts|| Source is within 2^14 range.  To perform the int operation,| move it to d0.|src_in:	fmovex		a6@(ETEMP),fp0	| move in src for int	fmovel		#rz_mode,fpcr	| force rz for src conversion	fmovel		fp0,d0		| int src to d0	fmovel		#0,FPSR		| clr status from above	tstw		a6@(ETEMP)	| check src sign	jlt 		src_neg|| Source is positive.  Add the src to the dest exponent.| The result can be denormalized, if src = 0, or overflow,| if the result of the add sets a bit in the upper word.|src_pos:	tstw		d1		| check for denorm	jeq 		dst_dnrm	addl		d0,d1		| add src to dest exp	jeq 		__x_denorm	| if zero, result is denorm	cmpil		#0x7fff,d1	| test for overflow	jge 		__x_ovfl	tstb		a6@(L_SCR1)	jeq 		spos_pos	orw		#0x8000,d1spos_pos:	movew		d1,a6@(FPTEMP)	| result in FPTEMP	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	| write result to fp0	rts__x_ovfl:	tstb		a6@(L_SCR1)	jeq 		sovl_pos	orw		#0x8000,d1sovl_pos:	movew		a6@(FPTEMP),a6@(ETEMP)	| result in ETEMP	movel		a6@(FPTEMP_HI),a6@(ETEMP_HI)	movel		a6@(FPTEMP_LO),a6@(ETEMP_LO)	jra 		__x_t_ovfl2__x_denorm:	tstb		a6@(L_SCR1)	jeq 		den_pos	orw		#0x8000,d1den_pos:	tstl		a6@(FPTEMP_HI)	| check j bit	jlt 		nden_exit	| if set, not denorm	movew		d1,a6@(ETEMP)	| input expected in ETEMP	movel		a6@(FPTEMP_HI),a6@(ETEMP_HI)	movel		a6@(FPTEMP_LO),a6@(ETEMP_LO)	orl		#__x_unfl_bit,a6@(USER_FPSR)	| set unfl	lea		a6@(ETEMP),a0	jra 		__x_t_resdnrmnden_exit:	movew		d1,a6@(FPTEMP)	| result in FPTEMP	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	| write result to fp0	rts|| Source is negative.  Add the src to the dest exponent.| (The result exponent will be reduced).  The result can be| denormalized.|src_neg:	addl		d0,d1		| add src to dest	jeq 		__x_denorm	| if zero, result is denorm	jlt 		fix_dnrm	| if negative, result is|					| needing denormalization	tstb		a6@(L_SCR1)	jeq 		__x_sneg_pos	orw		#0x8000,d1__x_sneg_pos:	movew		d1,a6@(FPTEMP)	| result in FPTEMP	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	| write result to fp0	rts|| The result exponent is below denorm value.  Test for catastrophic| underflow and force zero if true.  If not, try to shift the| mantissa right until a zero exponent exists.|fix_dnrm:	cmpiw		#0xffc0,d1	| lower bound for normalization	jlt 		fix_unfl	| if lower, catastrophic unfl	movew		d1,d0		| use d0 for exp	movel		d2,a7@-	| free d2 for norm	movel		a6@(FPTEMP_HI),d1	movel		a6@(FPTEMP_LO),d2	clrl		a6@(L_SCR2)fix_loop:	addw		#1,d0		| drive d0 to 0	lsrl		#1,d1		| while shifting the	roxrl		#1,d2		| mantissa to the right	jcc 		no_carry	st		a6@(L_SCR2)	| use L_SCR2 to capture inexno_carry:	tstw		d0		| it is finished when	jlt 		fix_loop	| d0 is zero or the mantissa	tstb		a6@(L_SCR2)	jeq 		tst_zero	orl		#__x_unfl_inx_mask,a6@(USER_FPSR)|					| set unfl, aunfl, ainex|| Test for zero. If zero, simply use fmovel to return +/- zero| to the fpu.|tst_zero:	clrw		a6@(FPTEMP_EX)	tstb		a6@(L_SCR1)	| test for sign	jeq 		tst_con	orw		#0x8000,a6@(FPTEMP_EX) | set sign bittst_con:	movel		d1,a6@(FPTEMP_HI)	movel		d2,a6@(FPTEMP_LO)	movel		a7@+,d2	tstl		d1	jne 		not_zero	tstl		a6@(FPTEMP_LO)	jne 		not_zero|| Result is zero.  Check for rounding mode to set lsb.  If the| mode is rp, and the zero is positive, return smallest denorm.| If the mode is rm, and the zero is negative, return smallest| negative denorm.|	btst		#5,a6@(fpcr_MODE) | test if rm or rp	jeq 		no_dir	btst		#4,a6@(fpcr_MODE) | check which one	jeq 		zer_rmzer_rp:	tstb		a6@(L_SCR1)	| check sign	jne 		no_dir		| if set, neg op, no inc	movel		#1,a6@(FPTEMP_LO) | set lsb	jra 		sm_dnrmzer_rm:	tstb		a6@(L_SCR1)	| check sign	jeq 		no_dir		| if clr, neg op, no inc	movel		#1,a6@(FPTEMP_LO) | set lsb	orl		#neg_mask,a6@(USER_FPSR) | set N	jra 		sm_dnrmno_dir:	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	/* | use fmovel to set cc's */	rts|| The rounding mode changed the zero to a smallest denorm. Call| __x_t_resdnrm with exceptional operand in ETEMP.|sm_dnrm:	movel		a6@(FPTEMP_EX),a6@(ETEMP_EX)	movel		a6@(FPTEMP_HI),a6@(ETEMP_HI)	movel		a6@(FPTEMP_LO),a6@(ETEMP_LO)	lea		a6@(ETEMP),a0	jra 		__x_t_resdnrm|| Result is still denormalized.|not_zero:	orl		#__x_unfl_mask,a6@(USER_FPSR) | set unfl	tstb		a6@(L_SCR1)	| check for sign	jeq 		fix_exit	orl		#neg_mask,a6@(USER_FPSR) | set Nfix_exit:	jra 		sm_dnrm|| The result has underflowed to zero. Return zero and set| unfl, aunfl, and ainex.|fix_unfl:	orl		#__x_unfl_inx_mask,a6@(USER_FPSR)	btst		#5,a6@(fpcr_MODE) | test if rm or rp	jeq 		no_dir2	btst		#4,a6@(fpcr_MODE) | check which one	jeq 		zer_rm2zer_rp2:	tstb		a6@(L_SCR1)	| check sign	jne 		no_dir2		| if set, neg op, no inc	clrl		a6@(FPTEMP_EX)	clrl		a6@(FPTEMP_HI)	movel		#1,a6@(FPTEMP_LO) | set lsb	jra 		sm_dnrm		| return smallest denormzer_rm2:	tstb		a6@(L_SCR1)	| check sign	jeq 		no_dir2		| if clr, neg op, no inc	movew		#0x8000,a6@(FPTEMP_EX)	clrl		a6@(FPTEMP_HI)	movel		#1,a6@(FPTEMP_LO) | set lsb	orl		#neg_mask,a6@(USER_FPSR) | set N	jra 		sm_dnrm		| return smallest denormno_dir2:	tstb		a6@(L_SCR1)	jge 		pos_zeroneg_zero:	clrl		a6@(FP_SCR1)	| clear the exceptional operand	clrl		a6@(FP_SCR1+4)	| for __x_gen_except.	clrl		a6@(FP_SCR1+8)	.long 0xf23c4400,0x80000000	/*  fmoves  &0x80000000,fp0 */	rtspos_zero:	clrl		a6@(FP_SCR1)	| clear the exceptional operand	clrl		a6@(FP_SCR1+4)	| for __x_gen_except.	clrl		a6@(FP_SCR1+8)	.long 0xf23c4400,0x00000000	/*  fmoves  &0x00000000,fp0 */	rts|| The destination is a denormalized number.  It must be handled| by first shifting the bits in the mantissa until it is normalized,| then adding the remainder of the source to the exponent.|dst_dnrm:	moveml		d2/d3,a7@-	movew		a6@(FPTEMP_EX),d1	movel		a6@(FPTEMP_HI),d2	movel		a6@(FPTEMP_LO),d3dst_loop:	tstl		d2		| test for normalized result	jlt 		dst_norm	| exit loop if so	tstl		d0		| otherwise, test shift count	jeq 		dst_fin		| if zero, shifting is done	subil		#1,d0		| dec src	lsll		#1,d3	roxll		#1,d2	jra 		dst_loop|| Destination became normalized.  Simply add the remaining| portion of the src to the exponent.|dst_norm:	addw		d0,d1		| dst is normalized|  add src	tstb		a6@(L_SCR1)	jeq 		dnrm_pos	orl		#0x8000,d1dnrm_pos:	movemw		d1,a6@(FPTEMP_EX)	moveml		d2,a6@(FPTEMP_HI)	moveml		d3,a6@(FPTEMP_LO)	fmovel		a6@(USER_FPCR),fpcr	fmovex		a6@(FPTEMP),fp0	moveml		a7@+,d2/d3	rts|| Destination remained denormalized.  Call t_excdnrm with| exceptional operand in ETEMP.|dst_fin:	tstb		a6@(L_SCR1)	| check for sign	jeq 		dst_exit	orl		#neg_mask,a6@(USER_FPSR) | set N	orl		#0x8000,d1dst_exit:	movemw		d1,a6@(ETEMP_EX)	moveml		d2,a6@(ETEMP_HI)	moveml		d3,a6@(ETEMP_LO)	orl		#__x_unfl_mask,a6@(USER_FPSR) | set unfl	moveml		a7@+,d2/d3	lea		a6@(ETEMP),a0	jra 		__x_t_resdnrm|| Source is outside of 2^14 range.  Test the sign and branch| to the appropriate exception handler.|src_out:	tstb		a6@(L_SCR1)	jeq 		scro_pos	orl		#0x8000,d1scro_pos:	movel		a6@(FPTEMP_HI),a6@(ETEMP_HI)	movel		a6@(FPTEMP_LO),a6@(ETEMP_LO)	tstw		a6@(ETEMP)	jlt 		res_negres_pos:	movew		d1,a6@(ETEMP)	| result in ETEMP	jra 		__x_t_ovfl2res_neg:	movew		d1,a6@(ETEMP)	| result in ETEMP	lea		a6@(ETEMP),a0	jra 		__x_t_unfl|	end