patch-1.3.94 linux/arch/m68k/fpsp040/sgetem.S

• Lines: 142
• Date: Sat Feb 24 22:58:44 1996
• Orig file: v1.3.93/linux/arch/m68k/fpsp040/sgetem.S
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.93/linux/arch/m68k/fpsp040/sgetem.S linux/arch/m68k/fpsp040/sgetem.S
@@ -0,0 +1,141 @@
+|
+|	sgetem.sa 3.1 12/10/90
+|
+|	The entry point sGETEXP returns the exponent portion 
+|	of the input argument.  The exponent bias is removed
+|	and the exponent value is returned as an extended 
+|	precision number in fp0.  sGETEXPD handles denormalized
+|	numbers.
+|
+|	The entry point sGETMAN extracts the mantissa of the 
+|	input argument.  The mantissa is converted to an 
+|	extended precision number and returned in fp0.  The
+|	range of the result is [1.0 - 2.0).
+|
+|
+|	Input:  Double-extended number X in the ETEMP space in
+|		the floating-point save stack.
+|
+|	Output:	The functions return exp(X) or man(X) in fp0.
+|
+|	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+|	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA 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.
+
+|SGETEM	idnt	2,1 | Motorola 040 Floating Point Software Package
+
+	|section 8
+
+	.include "fpsp.h"
+
+	|xref	nrm_set
+
+|
+| This entry point is used by the unimplemented instruction exception
+| handler.  It points a0 to the input operand.
+|
+|
+|
+|	SGETEXP
+|
+
+	.global	sgetexp
+sgetexp:
+	movew	LOCAL_EX(%a0),%d0	|get the exponent
+	bclrl	#15,%d0		|clear the sign bit
+	subw	#0x3fff,%d0	|subtract off the bias
+	fmovew  %d0,%fp0		|move the exp to fp0
+	rts
+
+	.global	sgetexpd
+sgetexpd:
+	bclrb	#sign_bit,LOCAL_EX(%a0)
+	bsr	nrm_set		|normalize (exp will go negative)
+	movew	LOCAL_EX(%a0),%d0	|load resulting exponent into d0
+	subw	#0x3fff,%d0	|subtract off the bias
+	fmovew	%d0,%fp0		|move the exp to fp0
+	rts
+|
+|
+| This entry point is used by the unimplemented instruction exception
+| handler.  It points a0 to the input operand.
+|
+|
+|
+|	SGETMAN
+|
+|
+| For normalized numbers, leave the mantissa alone, simply load
+| with an exponent of +/- $3fff.
+|
+	.global	sgetman
+sgetman:
+	movel	USER_FPCR(%a6),%d0
+	andil	#0xffffff00,%d0	|clear rounding precision and mode
+	fmovel	%d0,%fpcr		|this fpcr setting is used by the 882
+	movew	LOCAL_EX(%a0),%d0	|get the exp (really just want sign bit)
+	orw	#0x7fff,%d0	|clear old exp
+	bclrl	#14,%d0	 	|make it the new exp +-3fff
+	movew	%d0,LOCAL_EX(%a0)	|move the sign & exp back to fsave stack
+	fmovex	(%a0),%fp0	|put new value back in fp0
+	rts
+
+|
+| For denormalized numbers, shift the mantissa until the j-bit = 1,
+| then load the exponent with +/1 $3fff.
+|
+	.global	sgetmand
+sgetmand:
+	movel	LOCAL_HI(%a0),%d0	|load ms mant in d0
+	movel	LOCAL_LO(%a0),%d1	|load ls mant in d1
+	bsr	shft		|shift mantissa bits till msbit is set
+	movel	%d0,LOCAL_HI(%a0)	|put ms mant back on stack
+	movel	%d1,LOCAL_LO(%a0)	|put ls mant back on stack
+	bras	sgetman
+
+|
+|	SHFT
+|
+|	Shifts the mantissa bits until msbit is set.
+|	input:
+|		ms mantissa part in d0
+|		ls mantissa part in d1
+|	output:
+|		shifted bits in d0 and d1
+shft:
+	tstl	%d0		|if any bits set in ms mant
+	bnes	upper		|then branch
+|				;else no bits set in ms mant
+	tstl	%d1		|test if any bits set in ls mant
+	bnes	cont		|if set then continue
+	bras	shft_end	|else return
+cont:
+	movel	%d3,-(%a7)	|save d3
+	exg	%d0,%d1		|shift ls mant to ms mant
+	bfffo	%d0{#0:#32},%d3	|find first 1 in ls mant to d0
+	lsll	%d3,%d0		|shift first 1 to integer bit in ms mant
+	movel	(%a7)+,%d3	|restore d3
+	bras	shft_end
+upper:
+
+	moveml	%d3/%d5/%d6,-(%a7)	|save registers
+	bfffo	%d0{#0:#32},%d3	|find first 1 in ls mant to d0
+	lsll	%d3,%d0		|shift ms mant until j-bit is set
+	movel	%d1,%d6		|save ls mant in d6
+	lsll	%d3,%d1		|shift ls mant by count
+	movel	#32,%d5
+	subl	%d3,%d5		|sub 32 from shift for ls mant
+	lsrl	%d5,%d6		|shift off all bits but those that will
+|				;be shifted into ms mant
+	orl	%d6,%d0		|shift the ls mant bits into the ms mant
+	moveml	(%a7)+,%d3/%d5/%d6	|restore registers
+shft_end:
+	rts
+
+	|end