www.pudn.com > 8255_code_lib.rar > DIOFNC10.C

/*- 
 *  ---------------------------------------------------------------------- 
 *  File        :   DIOFNC10.C 
 *  Creator     :   Blake Miller 
 *  Version     :   01.01.00            February 1991 
 *  Language    :   Microsoft Quick C   Version 2.0 
 *  Purpose     :   Intel 8255 Compatible Digital IO Functions 
 *                  80X86 IN Instruction Function 
 *  ---------------------------------------------------------------------- 
 *  WARNING: Inline Assembly Language Here! 
 *  ---------------------------------------------------------------------- 
 *  Revision History: 
 *  022891 BVM  :   Change int to short. 
 *  070490 BVM  :   Creation 
 *  ---------------------------------------------------------------------- 
 */ 
 
#define     DIOFNC10_C_DEFINED  1 
#undef      DIOFNC10_C_DEFINED 
 
void dio_bget (short d_port, unsigned char *d_byte); 
 
/*- DIO : Byte Get ---------------------------** 
 *  Read a byte from one of the 80X86 ports. 
 *  Duplicates the library function inp() 
 */ 
void dio_bget (short d_port, unsigned char *d_byte) 
	{ 
	unsigned char   t_byte = 0; /* temporary byte   */ 
 
	/*  set port address 
	 *  get data into AL 
	 *  store data into temporary variable 
	 *  Note: Use temporary variable because ASM has no idea 
	 *  what a pointer to an unsigned char is! 
	 */ 
	_asm    { 
		PUSH    AX 
		PUSH    DX 
 
		MOV     DX, d_port 
		IN      AL, DX          ; get byte into AL 
		MOV     t_byte, AL      ; transfer data to C 
 
		POP     DX 
		POP     AX 
		} 
 
	*d_byte = t_byte;   /* transfer data to caller  */ 
	} 
 
/*- 
 *  ---------------------------------------------------------------------- 
 *  END DIOFNC10.C Source File 
 *  ---------------------------------------------------------------------- 
 */