需要和8255程序一同连接，注意初始化参数与引脚连接方式有关。 .286public _getcharextrn _i8255:near,_outpb:near,_inpa:neardseg segment para public 'DATA'INVALID equ 0ffhg_ch_tbl db 'C','D','E','F','B','A','9','8' db '4','5','6','7','3','2','1','0' db 'W','X','Y','S','R','P','M','G'dseg endscseg segment para public 'CODE' assume cs:cseg,ds:dsegstart:_getchar proc ;char getchar(){ call _testkey ; char al = testkey(); cmp al,0ffh ; if(al == INVALID){ je gc_ret ; return INVALID; ; } ; else{ call _scankey ; al = scankey(); cmp al,INVALID ; if(al == INVALID) return INVALID; je gc_ret mov bx,ax ; return g_ch_tbl[al]; mov al,g_ch_tbl[bx] ; } retgc_ret: mov ax,INVALID ret_getchar endp ;} _testkey proc ;char testkey() mov al,07h ;{ xor al,0ffh call _outpb ; outpb(0f8h); call _inpa ; return inpa(); ret_testkey endp ;} _scankey proc ;int scankey(){ mov bx,0 ; int code = 0; mov dx,0 ; int index = 0; mov ax,1 ; int outcode = 1; xor ax,0ffffh mov cx,3 ; for(int i=0;i<3;i++)for_3: ; { push ax call _scanline ; code = scanline(~outcode); mov bx,ax pop ax cmp bl,0ffh ; if(code != INVALID){ je for_3_next push ax mov ax,bx call _transcode ; index += transcode(code); add dx,ax pop ax call _waitup ; waitup(~outcode,code); mov ax,dx ret ; return index; ; }for_3_next: ; else{ add dx,8 ; index += 8; rol ax,1 ; outcode << 1; loop for_3 ; } mov ax,INVALID ; } ret ; return INVALID;_scankey endp ;} _scanline proc ;char scanline(char outcode){ call _outpb ; outpb(outcode); call _inpa ; return inpa(); ret_scanline endp ;} _transcode proc ;int transcode(char code){ push bx mov bx,1 ; char test = 1; xor bl,0ffh mov cx,8 ; for(int i=0;i<8;i++)tc_lp: ; { cmp al,bl ; if(code == ~test) je tc_ret ; return 8-i; rol bl,1 ; test << 1; loop tc_lp ; }tc_ret: mov ax,8 sub ax,cx pop bx ret_transcode endp ;} _waitup proc ;void waitup(char outcode,char code) pusha ;{ mov dx,axwu_lp: ;wu_lp: mov ax,dx call _scanline ; char test = scanline(outcode); cmp ax,bx ; if(test == code) je wu_lp ; goto wu_lp; popa ret_waitup endp ;} cseg ends end start
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