Assembler

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8088, 8087
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. 7.18
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- C3 C0; C3
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Microsoft (R) Macro Assembler Version 5.00 1/1/80 04:04:18
. 7.18 8087 Page 1-1
 
PAGE ,132
TITLE . 7.18 8087
 
0000 CODE SEGMENT
ASSUME CS:CODE,DS:CODE
 
0000 WORD_INTEGER LABEL WORD
0000 SHORT_INTEGER LABEL DWORD
0000 SHORT_REAL LABEL DWORD
0000 LONG_REAL LABEL QWORD
 
0000 9B D8 D1 FCOM
0003 9B D8 D2 FCOM ST(2)
0006 9B DE 16 0000 R FICOM WORD_INTEGER
000B 9B D8 16 0000 R FCOM SHORT_REAL
0010 9B D8 D9 FCOMP
0013 9B DA 1E 0000 R FICOMP SHORT_INTEGER
0018 9B DC 1E 0000 R FCOMP LONG_REAL
001D 9B DE D9 FCOMPP
0020 9B D9 E4 FTST
0023 9B D9 E5 FXAM
 
 
0026 CODE ENDS
END
 
. 7.18 8087
 
8087 C3 C0
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C3 C0. ,
8087
8088,

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3 0
--------------------------------------------------------------
0 0 ST >
0 1 ST <
1 0 ST =
1 1 ST
--------------------------------------------------------------
 
. 7.19
 
. 7.18 ,
FCOM, , FCOM
FICOM . FCOMP
FICOMP FCOM FICOM, ,
8087
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8087, ,
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Microsoft (R) Macro Assembler Version 5.00 1/1/80 04:04:23
. 7.20 Page 1-1
 
 
PAGE ,132
TITLE . 7.20
 
0000 CODE SEGMENT
ASSUME CS:CODE,DS:CODE
 
0000 WORD_INTEGER LABEL WORD
0000 ???? STATUS_WORD DW ?
 
;----- WORD_PTR 8087
 
0002 9B DE 16 0000 R FICOM WORD_INTEGER ; ST
0007 9B DD 3E 0000 R FSTSW STATUS_WORD ; 8087
000C 9B FWAIT ;
000D 8A 26 0001 R MOV AH,BYTE PTR STATUS_WORD+1
0011 9E SAHF ; (C0=CF,C3=ZF)
0012 72 02 JB CONTINUE ; C0, 0
0014 75 00 JNE ST_GREATER ; C3
0016 ST_EQUAL: ; , C3=1,C0=0 -
; ... ;
0016 ST_GREATER: ; , C3=0,C0=0 -
; ... ; 8087 WORD_PTR
0016 CONTINUE:
0016 75 00 JNE ST_LESS ; C3
0018 UNORDERED: ; , C3=1,C0=1 - -
; ... ;
0018 ST_LESS: ; , C3=0,C0=1 -
; ... ; 8087 WORD_PTR
 
0018 CODE ENDS
END
 
. 7.20
 
FCOMPP .
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. 7.21 .
 
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8087,
FXAM;
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- 8087 .
8087 ,
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C3 C2 C1 C0 3 2 1 0
---------------------------------------------------------------------------------------------------
0 0 0 0 + 1 0 0 0 + 0
0 0 0 1 + NAN 1 0 0 1
0 0 1 0 - 1 0 1 0 - 0
0 0 1 1 - NAN 1 0 1 1
0 1 0 0 + 1 1 0 0 +
0 1 0 1 + 1 1 0 1
0 1 1 0 - 1 1 1 0 -
0 1 1 1 - 1 1 1 1
---------------------------------------------------------------------------------------------------

. 7.21

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