setprec.87

数学运算库源码

;
; Microsoft MASM subroutines for setting coprocessor precision
;
.286
.287
_TEXT	SEGMENT  BYTE PUBLIC 'CODE'
_TEXT	ENDS
CONST	SEGMENT  WORD PUBLIC 'CONST'
CONST	ENDS
_BSS	SEGMENT  WORD PUBLIC 'BSS'
_BSS	ENDS
_DATA	SEGMENT  WORD PUBLIC 'DATA'
_DATA	ENDS
DGROUP	GROUP	CONST,	_BSS,	_DATA
	ASSUME  CS: _TEXT, DS: DGROUP, SS: DGROUP, ES: DGROUP
EXTRN	__fac:QWORD

_BSS      SEGMENT
EXTRN	__fltused:NEAR
_BSS      ENDS


; exception masks (1 = masked)
;   1  invalid operation
;   2  denormalized operand
;   4  zero divide
;   8  overflow
;  10  underflow
;  20  precision

_DATA SEGMENT

; double precision setting
;;ctlwrd dw 01230h ; note this traps on denormal operands!
;;ctld dw 0133fh   ; this doesn't trap
ctld dw 01230h

; single precision
ctls dw 01030h

; long double precision
ctlld dw 01320h

_DATA ENDS

	ASSUME  CS: _TEXT

_TEXT SEGMENT
; Set coprocessor to single precision float
	PUBLIC	_sprec
_sprec	PROC NEAR
	fclex
	fwait
	finit
	fwait
	fldcw word ptr ctls
	fwait
	ret
_sprec ENDP

; set coprocessor to long double precision
	PUBLIC	_ldprec
_ldprec PROC NEAR
	fclex
	fwait
	finit
	fwait
	fldcw word ptr ctlld
	fwait
	ret
_ldprec ENDP

; set coprocessor to double precision
	PUBLIC	_dprec
_dprec PROC NEAR
	fclex
	fwait
	finit
	fwait
	fldcw word ptr ctld
	fwait
	ret
_dprec ENDP


; get a double promoted to long double size
; getld( &doub, &ldoub );
	PUBLIC	_getld
_getld	PROC NEAR
	push bp
	mov bp,sp
	push bx
	mov bx, word ptr [bp+4]
;	fld st(0)
	fld qword ptr [bx]
	mov bx, word ptr [bp+6]
	fstp tbyte ptr [bx]
	mov bx, word ptr [bp+4]
	fld qword ptr [bx]
	mov bx, word ptr [bp+8]
	fstp qword ptr [bx]
	pop bx
	pop bp
	ret
_getld	ENDP

	PUBLIC	_getprec
_getprec	PROC NEAR
	push bp
	mov bp,sp
	sub sp,4
	fstcw [bp-4]
	fwait
	mov ax,[bp-4]
	add sp,4
	pop bp
	ret
_getprec	ENDP


	PUBLIC	_fpclear
_fpclear	PROC NEAR
	push bp
	mov bp,sp
	fnclex
	fwait
	pop bp
	ret
_fpclear	ENDP


	PUBLIC	_noexcept
_noexcept	PROC NEAR
	push bp
	mov bp,sp
	push ax
	sub sp,4
	fnclex
	fwait
	fstcw [bp-4]
	fwait
	mov ax,[bp-4]
	and ax,0FFC0h
	or ax,003fh
	mov [bp-4],ax
	fldcw [bp-4]
	add sp,4
	pop ax
	pop bp
	ret
_noexcept	ENDP

;; single precision square root
;; assumes coprocessor precision already set up
;; return value in static __fac
;	PUBLIC	_sqrtf
;_sqrtf	PROC NEAR
;	push bp
;	mov bp,sp
;	fld	DWORD PTR [bp+4]
;	fsqrt
;	fwait	
;	fstp	DWORD PTR __fac
;	mov	ax,OFFSET __fac
;	mov	sp,bp
;	pop bp
;	ret
;_sqrtf	ENDP
;
;
;; double precision square root
;; assumes coprocessor precision already set up
;; return value in static __fac
;	PUBLIC	_sqrt
;_sqrt	PROC NEAR
;	push bp
;	mov bp,sp
;	fld	QWORD PTR [bp+4]
;	fsqrt
;	fwait	
;	fstp	QWORD PTR __fac
;	mov	ax,OFFSET __fac
;	mov	sp,bp
;	pop bp
;	ret
;_sqrt	ENDP
;
;
;; long double precision square root
;; assumes coprocessor precision already set up
;; return value in fp register
;	PUBLIC	_sqrtl
;_sqrtl	PROC NEAR
;	push bp
;	mov bp,sp
;	fld tbyte ptr [bp+4]
;	fsqrt
;	fwait	
;	mov	sp,bp
;	pop bp
;	ret
;_sqrtl	ENDP
;

_TEXT ENDS
END