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Technotools
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Technotools (Chestnut CD-ROM)(1993).ISO
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lang_c
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mikecom
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carrier.asm
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Assembly Source File
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1987-05-17
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1KB
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31 lines
title GET CARRIER STATUS
include subfx.h
; Mike Dumdei, 6 Holly Lane, Texarkana TX 75503
;******************************************************************************
; ASYNC_CARRIER -- Returns TRUE (1) if carrier is present else returns
; FALSE (0). Returns R_NOPORT (-1) if invalid port.
;******************************************************************************
begseg COMM_TEXT
publicproc _async_carrier
push bp
mov bp,sp
push si ;stack frame setup
call __ck_port_arg ;ck if valid, load pointers
jz carr_exit ;bad arg if ZR flag set
xor ax,ax ;set up in case no carrier
test MSR_VAL,B_CD ;ck MSR value for CD (RLSD)
jz carr_exit ;ZR test result == no carrier
inc ax ;NZ test result == carrier present
carr_exit:
pop si
pop bp
ret ;restore regs and exit
_async_carrier endp
endseg COMM_TEXT
end