dexp.u

操作系统SunOS 4.1.3版本的源码

|*	@(#)dexp.u 1.1 92/07/30 Copyright Sun Microsystems, Inc.  1988
|* 
|* hi: stored in SCRATCH_10 --> DA
|* lo: stored in SCRATCH_11 --> DB
|* z:  stored in SCRATCH_12 --> DC
|* k:  stored in SCRATCH_13 --> DD
|* c:  stored in SCRATCH_14 --> DE
|*
|* First get abs(x) and store it in the 'C' register in the TI8847.
routine xd.ex 001000001101	dnop enra loaddp halt;		regtoti;	rcsmsw imm2;
	call dnotfinx;		dabs enra loaddp halt;		regtoti;	rcslsw imm2;
|* Compare abs(x) with ln2/2
	jgt xgtln2_2;		dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dcmp aluacreg enrb loaddp halt;	regtoti;	rcslsw ptr5;		ptr5!c_dln2_onehalf
|* Check to see whether abs(x) < twom18.  If so, return x + one.  abs(x) is in C reg.
	;			dnop;				;		ptr5; 		ptr5!c_dtwom18
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dcmp aluacreg enrb loaddp halt;	regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr5;		ptr5!c_ssin
	jlt chktwom28;		smul enra enrb halt;		regtoti;	rcssp ptr5;
|* If not, z=x, and k = 0.
	;			;				regtotmp;	rcslsw ptr2;		
	jtierr hang cstat;	dnop halt;			regtotmp;	rcsmsw ptr2;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDC
	;			dnop;				tmptoreg;	rcsmsw ptr5;
	;			dnop;				tmptoreg;	rcslsw ptr5;
|* Store k=0 in SCRATCH_13
	;			dnop;				;		ptr5;		ptr5!c_sizero
	;			dnop;				regtotmp;	rcssp ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDD
	call z.inrange;		dnop;				tmptoreg;	rcssp ptr5;

chktwom28:
	jtierr hang cstat;	dnop halt;			;		;
	;			dnop halt;			;		ptr5;	ptr5!c_dtwom28
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dcmp aluacreg enrb loaddp halt;	regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr2;
	jlt retxsq;		dnop enra enrb loaddp halt;	regtoti;	rcsmsw ptr2;
	;			dmul enra enrb loaddp halt;	regtoti;	rcslsw ptr2;
|* Compute 1 + x + 0.5x^2 and store in pointer 1.
	;			dmul;				;		ptr5;		ptr5!dhalf
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dmul mulbmul enra loaddp halt;  regtoti;	rcslsw ptr5;
	;			dmul mulbmul;			;		;
	;			dadd aluamul halt;		;		ptr5;		ptr5!done
	;			dadd aluamul halt;		;		ptr5;		ptr5!done
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dadd alubalu enra loaddp halt;	regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr1;
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr1;
	call idle1;		dnop tioe timsw halt;		titoreg;	rcsmsw ptr1;
retxsq:
|* Compute 1 + x and store in pointer 2.
	;			dmul;				;		ptr5;		ptr5!done
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dadd enra loaddp halt;		regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr1;
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr1;
	call idle1;		dnop tioe timsw halt;		titoreg;	rcsmsw ptr1;
xgtln2_2:
|* abs(x) is greater than ln2/2:
|* Now check whether abs(x) <= ln2 * 3/2
	;			dnop;				;		ptr5;	ptr5!c_ssin
	jle xlteln2t1.5;	smul enra enrb halt;		regtoti;	rcssp ptr5;
        ;                       smul;				;               ptr5;	ptr5!dzero
        jtierr hang cstat;	halt;				;		ptr5;
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dnop enrb loaddp halt;		regtoti;	rcslsw ptr5;
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr2;
	;			dcmp enra loaddp halt;		regtoti;	rcslsw ptr2;
	;			dnop;				;		ptr5;	ptr5!c_dthrsh1
	jlt xlzero;		dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dcmp aluacreg enrb loaddp halt;	regtoti;	rcslsw ptr5;
|* Need to check if abs(x) > thrsh1.  If so, then Bailout.overflow.
	;			dnop;				;		ptr5;	ptr5!c_dinvln2		
	jgt bail.ov;		dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;	
|* Multiply x * invln2  (Note: X is in RA)
	;			dmul enrb loaddp halt;		regtoti;	rcslsw ptr5;
	;			dmul;				;		;		
	;			dnop srccmul clkcc;		;		;
pmpt5:
|* Convert double to integer: k in c register. Save in SCRATCH 13 register.
	;			dcvtint aluacreg;		;		;		
	;			dnop;				;		ptr5;		ptr5!0x700+0xDD
|* Calculate t= double k
	;			dfloat enra tioe tisp loaddp halt;titoreg;	rcssp ptr5;
	;			dfloat enra tioe tisp loaddp halt;;		;
	;			dnop;				;		;
	;			dnop enra tioe timsw loaddp halt;;		;
	;			dnop enra tioe tilsw loaddp halt;;		;
	;			dnop;				;		ptr5;		ptr5!c_dln2hi
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dmul enrb loaddp halt; 		regtoti; 	rcslsw ptr5;
	;			dmul;				;		ptr2;
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr2;
|* Store x - (result) in SCRATCH_10.
	;			drsub aluamul enrb loaddp halt;	regtoti;	rcslsw ptr2;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDA
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr5;
	;			dnop tioe timsw halt;		titoreg;	rcsmsw ptr5;
|* get lo = t*ln2lo.  Store in SCRATCH_11 and input to RB.
	;			dnop;				;		ptr5;		ptr5!c_dln2lo
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dmul enrb loaddp halt;		regtoti;	rcslsw ptr5;
	;			dmul;				;		;
	;			dnop;				;		ptr5;		ptr5!0x700+0x0DB
|* load 'lo' in RB and call calcz = hi - lo.
	;			dnop enrb tioe timsw loaddp halt;titoreg;	rcsmsw ptr5;
	call calcz;		dnop enrb tioe tilsw loaddp halt;titoreg;	rcslsw ptr5;
xlzero:
|* Need to check if abs(x) > thrsh2.  If so, then Bailout.underflow.
	;			dnop;				;		ptr5;	ptr5!c_dthrsh2
	;			dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dcmp aluacreg enrb loaddp halt;	regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr5;	ptr5!c_dinvln2
	jgt bail.under;		dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;	
	;			dmul enrb loaddp halt;		regtoti;	rcslsw ptr5;
|* Multiply x * invln2  (Note: X is in RA) 
	;			dmul;				;		;
|* Will store in 'C' register, since abs(x) is not needed from here on.
	call pmpt5;		dnop srccmul clkcc;		;		;
bail.ov:
|* Load maxnorm and square it.  Will cause overflow.  Go to bail.out
	;			;				;		ptr5;		ptr5!smaxnorm
	;			smul enra enrb halt;		regtoti;	rcssp ptr5;
	;			;				;		;
	call bail.out cstat;	halt;				;		;
bail.under:
|* Load an 'underflowed' number and pass it through ALU.  jtierr to bail.out -- will report a
|* underflow.  If no tierr, then FAST mode is on, so return zero and do not signal an error.
	;			dnop;				;		ptr5;		ptr5!dminsub
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dnop enra loaddp halt;		regtoti;	rcslsw ptr5;
	;			dnop;				;		;
	jtierr bail.out cstat;	dnop halt;			;		;
	;			dnop;				;		ptr1;
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr1;
	call idle1;		dnop tioe timsw halt;		titoreg;	rcsmsw ptr1;
xlteln2t1.5:
|* abs(x) <= ln2 * 3/2
|* Now check whether x => 0.  X is left in RA.  0 in RB
	jtierr hang cstat;	dnop;				;		ptr2;
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr2;
	;			dcmp enra loaddp halt;		regtoti;	rcslsw ptr2;
	;			dnop;				;		ptr5;	ptr5!c_dln2hi
|* hi = x + ln2hi and store in SCRATCH_10
	jge ygezero;		dnop enrb loaddp halt;		regtoti;	rcsmsw ptr5;
|* Gets here if x<0, ie. msb(x)=1.
	;			dadd enrb loaddp halt;		regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDA
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr5;
	;			dnop tioe timsw halt;		titoreg;	rcsmsw ptr5;
|* Store k=-1 in SCRATCH_13
	;			dnop;				;		ptr5;		ptr5!c_simone
	;			dnop;				regtotmp;	rcssp ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDD
	;			dnop;				tmptoreg;	rcssp ptr5;
|* Store -ln2lo in SCRATCH_11 and in RB
	;			dnop;				;		ptr5;		ptr5!c_dmln2lo
	;			dnop enrb loaddp halt;		regtitmp;	rcsmsw ptr5;
	;			dnop enrb loaddp halt;		regtitmp;	rcslsw ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDB
	;			dnop;				tmptoreg;	rcsmsw ptr5;
	call calcz;		dnop;				tmptoreg;	rcslsw ptr5;

ygezero:
|* Gets here if x=>0, ie. msb(x)=0
	;			dsub;				;		;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDA
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr5;
	;			dnop tioe timsw halt;		titoreg;	rcsmsw ptr5;
|* Store k= 1 in SCRATCH_13
	;			dnop;				;		ptr5;		ptr5!c_sione
	;			dnop;				regtotmp;	rcssp ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDD
	;			dnop;				tmptoreg;	rcssp ptr5;
|* Store ln2lo in SCRATCH_11 and in RB
	;			dnop;				;		ptr5;		ptr5!c_dln2lo
	;			dnop enrb loaddp halt;		regtitmp;	rcsmsw ptr5;
	;			dnop enrb loaddp halt;		regtitmp;	rcslsw ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDB
	;			dnop;				tmptoreg;	rcsmsw ptr5;
	;			dnop;				tmptoreg;	rcslsw ptr5;
calcz:
	;			dnop;				;		ptr5;		ptr5!0x700+0xDA
	;			dnop enra loaddp halt;		regtoti;	rcsmsw ptr5;
	;			dsub enra loaddp halt;		regtoti;	rcslsw ptr5;
	;			dnop;				;		ptr5;		ptr5!0x700+0xDC
	;			dnop tioe tilsw halt;		titoreg;	rcslsw ptr5;