:
- Fxxx
(), - .
- Fxxx
, ST(0). ST ,
- Fixxx
, 16- 32-
- Fxxx ST, ST(i)
ST(i) , ST(0) - - .
- Fxxx ST(i), ST
ST(0) , ST(i) - .
- FxxxP ST(i), ST
ST(i) - , ST(0) - . ST(0)
"xxx" :
- ADD -
- SUB -
- SUBR - ,
- MUL -
- DIV -
- DIVR - ,
:
- FSQRT -
- FSCALE - 2
- FPREM -
- FRNDINT -
- FXTRACT -
- FABS -
- FCHS -
FSQRT ST(0).
FSCALE , ST(0). ST(0) , ST(1). :
ST(0) = ST(0) * 2n, -215 <= n <= +215
n - ST(1).
FPREM ST(0) ST(1). ST(0), ST(0).
, " ". C2 :
- 0 - , ST(0), ST(1),
- 1 - ST(0) ,
RNDINT ST(0) RC .
FABS ST(0). , FCHS ST(0) .
:
- (sin, cos, tg,...)
- (arcsin, arccos,...)
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|
|
- (xy, 2x, 10x, ex)
- (sh, ch, th,...)
- (arsh, arch, arcth,...)
:
- FPTAN
- FPATAN
- FYL2X y*log2(x)
- FYL2XP1 y*log2(x+1)
- F2XM1 2x-1
- FCOS cos(x)
- FSIN sin(x)
- FSINCOS sin(x) cos(x)
FPTAN ST(0), x y, y/x = tg(ST(0)).
y ST(0), x ( ST(1)). FPTAN :
0 <= ST(0) <= pi/4
, :
- sin(z) = 2*(y/x) / (1 + (y/x)2)
- cos(z) = (1 - (y/x)2) / (1 + (y/x)2)
- tg(z/2) = y/x;
- ctg(z/2) = x/y;
- cosec(z) = (1 + (y/x)2) / 2*(y/x)
- sec(z) = (1 + (y/x)2) / (1 - (y/x)2)
z - , ST(0) FPTAN, x y - ST(0) ST(1), .
FPATAN :
z=arctg(ST(0)/ST(1))=arctg(x/y).
x y ST(0) ST(1), . FPATAN :
0 < y < x
ST(0).
FYL2X y*log2(x), x y , , ST(0) ST(1). , . x .
, :
- : log2(x) = FYL2(x)
- : loge(x) = loge(2) * log2(x) = FYL2X(loge(2), x) = FYL2X(FLDLN2, x)
- : log10(x) = log10(2) * log2(x) = FYL2X (log10(2), x) = FYL2X(FLDLG2, x)
FYL2XP1 y*log2(x+1), x ST(0), y - ST(1). ST(0), .
x : 0 < x < 1 - 1/sqrt(2)
F2XM1 2x-1, x - ST(0). ST(0), : 0 <= x <= 0,5
FCOS cos(x). x ST(0), .
FSIN FCOS, ST(0).
FSINCOS ST(0). ST(1), - ST(0).
FPU
FLD1 - 1,0
FLDZ - +0,0
FLDPI - π
FLDL2E - log2(e)
FLDL2T - log2(10)
FLDLN2 - ln(2)
FLDLG2 - lg(2)
( ST(0)) .
:
.
:
, 
. , 
.
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, 
. , 
.
, 
, .
.Model Small
.586
.Data
res dq 0
a dq 3.0
b dq 10.0
const25 dw 25
const4 dw 4
const5 dw 5
status dw 0
.Code
;
; -
length_frac Equ [BP+4]
;
ten Equ word ptr [BP-2]
temp Equ word ptr [BP-4]
OutFloat Proc Near
ENTER 4, 0; 4
MOV ten, 10
ftst;
fstsw AX
SAHF
JNC @positiv
MOV AL, '-'; -
INT 29h
fchs;
@positiv:
fld1;
fld st(1);
fprem;
fsub st(2), st; -
fxch st(2);
XOR CX, CX;
;
@1:
fidiv ten;
fxch st(1); st st(1) fprem
fld st(1);
fprem; ( )
fsub st(2), st;
fimul ten; *10
fistp temp;
PUSH temp;
INC CX;
fxch st(1); ( , st(1) - 1)
ftst; 0?
fstsw AX
SAHF
JNZ @1; -
@2:; , .
POP AX
ADD AL, '0'
INT 29h
LOOP @2
; , . ,
fstp st; ,
fxch st(1)
ftst
fstsw AX
SAHF
JZ @quit;
MOV AL, '.'
INT 29h; -
MOV CX, length_frac;
@3:
fimul ten; 10
fxch st(1); fprem - st st(1)
fld st(1);
fprem;
fsub st(2), st;
fxch st(2)
fistp temp; temp
MOV AX, temp; , ,
OR AL, 30h; ascii
INT 29h;
fxch st(1); ( , st(1) - 1)
ftst
fstsw AX
SAHF; 0
LOOPNE @3
@quit:
fstp; .
fstp st
LEAVE;
RET 2
OutFloat EndP
func Proc Far
;PUSHA
finit;
fld qword ptr[b]; b
fld qword ptr[a]; a b
fcom st(1); a b
fstsw status;
MOV AH, byte ptr [status+1]
SAHF;
JA a_bigger; a
JB b_bigger; b
;
fild const25; 25 a b
JMP endcalc
a_bigger: ftst; a 0
fstsw status;
MOV AH, byte ptr [status+1]
SAHF;
JE error; a=0
fdivp st(1), st(0); b/a
fild const4; 4 b/a
fsubp st(1), st(0); b/a-4
JMP endcalc
b_bigger: fldz; 0 a b
fcomp st(2); b 0
; a b
fstsw status;
MOV AH, byte ptr [status+1]
SAHF;
JE error; b=0
fld st(0); a a b
fmul st(1), st(0); a a*a b
fmulp st(1), st(0); a*a*a b
fild const5; 5 a*a*a b
fsubp st(1), st(0); a*a*a-5 b
JMP endcalc
error:
fldz;
endcalc:
fstp res;
RET
func EndP
start:
MOV AX, @data
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MOV DS, AX
CALL func
XOR AX,AX
XOR BX,BX
XOR CX,CX
XOR DX,DX
finit;
fld res;
PUSH 10;
CALL outfloat
MOV AX,4c00h
INT 21h
End start
