AMX 86 - page 108

100

DAK

AMX Semaphore Manager

EXTRN AAINT:FAR ;enter ISP

EXTRN AAINX:FAR ;leave ISP

EXTRN AASMSIG:FAR ;signal to a semaphore

EXTRN _SYNCISP:WORD ;ISP synchronization semaphore id

;

DVC_CODE SEGMENT BYTE 'CODE'

;ASSUME CS:DVC_CODE

;

DVCISP PROC FAR

CALL AAINT ;tell AMX

Clear interrupt source

Check for event

MOV BX,_SYNCISP ;BX = semaphore id

CALL AASMSIG ;signal to semaphore

CALL AAINX ;tell AMX

IRET ;end of interrupt

;

DVCISP ENDP

;

DVC_CODE ENDS

In this example, we have mixed C and assembly language for illustration purposes.

Notice the use of the underscore character in the assembler code reference to variable

_SYNCISP. In C, the variable is named syncisp. The underscore is required because we

have assumed that the C compiler actually assigns the symbol name _syncisp to the

variable. Also note that we have assumed that the program linker can ignore upper/lower

case differences in symbols. Your C compiler and linker may behave differently.

Refer to the AMX 86 Tool Guide for a more complete description of C, assembler and

linking requirements when using AMX with a particular toolset.