49 lines
1.0 KiB
NASM
49 lines
1.0 KiB
NASM
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; This module defines subroutines to input and output bytes from
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; an auxiliary port.
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;
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; name inp -- input byte from port
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;
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; synopsis c = inp(port);
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; int c; returned byte
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; int port; port address
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;
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; description This function inputs a byte from the specified port
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; address and returns it as the function value.
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;
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PGROUP GROUP PROG
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PROG SEGMENT BYTE PUBLIC 'PROG'
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PUBLIC INP,OUTP
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ASSUME CS:PGROUP
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INP PROC NEAR
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PUSH BP ;SAVE BP
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MOV BP,SP
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MOV DX,[BP+4] ;GET PORT ADDRESS
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IN AL,DX ;GET INPUT BYTE
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XOR AH,AH ;CLEAR HIGH BYTE
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POP BP
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RET
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INP ENDP
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;
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; name outp -- output byte to port
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;
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; synopsis outp(port,c);
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; int port; port address
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; int c; byte to send
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;
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; description This function sends the specified character to
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; the specified port.
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;
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OUTP PROC NEAR
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PUSH BP ;SAVE BP
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MOV BP,SP
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MOV DX,[BP+4] ;GET PORT ADDRESS
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MOV AX,[BP+6] ;GET OUTPUT BYTE
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OUT DX,AL
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POP BP
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RET
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OUTP ENDP
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PROG ENDS
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END
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,SP
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MOV DX,[BP+4] ;GET PORT ADDRESS
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MOV AX,[BP+6]
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