systemcga.c

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/*******************
*Project: 80X86 32BIT MULTI TASKING OPERATING SYSTEM
*Description: driver for MC6845
*
*File: cga.c
*Author: Book Chen
*Date: 2010.01.01
********************
*/
#include "includes.h"

SYSTEM_CGA_CONTROL SystemCgaCtrl;

void SystemCgaInit(void){
    SystemCgaCtrl.CursorPosition=0;
    SystemCgaCtrl.CharacterAttribute=0x1F;
    SystemCgaScreenClean();
    SystemCgaCtrl.CharacterAttribute=0x0F;
    OutByte(SYSTEM_CGA_ADDRESS_PORT,SYSTEM_CGA_CLLR);
    OutByte(SYSTEM_CGA_DATA_PORT,((SystemCgaCtrl.CursorPosition/2)&0xff));
    OutByte(SYSTEM_CGA_ADDRESS_PORT,SYSTEM_CGA_CLHR);
    OutByte(SYSTEM_CGA_DATA_PORT,(((SystemCgaCtrl.CursorPosition/2)>>8)&0xff));
}

void SystemCgaCursorSet(void){
    OutByte(SYSTEM_CGA_ADDRESS_PORT,SYSTEM_CGA_CLLR);
    OutByte(SYSTEM_CGA_DATA_PORT,((SystemCgaCtrl.CursorPosition/2)&0xff));
    OutByte(SYSTEM_CGA_ADDRESS_PORT,SYSTEM_CGA_CLHR);
    OutByte(SYSTEM_CGA_DATA_PORT,(((SystemCgaCtrl.CursorPosition/2)>>8)&0xff));
}

void SystemCgaScrollUp(void){
    U32 i;
    U8 ByteValue;
    
    for(i=0;i<3840;i++){
        ByteValue=SystemCgaByteRead(i+160);
        SystemCgaByteWrite(i,ByteValue);
    }
    for(i=3840;i<4000;i=i+2){
        SystemCgaByteWrite(i,' ');
        SystemCgaByteWrite(i+1,SystemCgaCtrl.CharacterAttribute);
    }
    SystemCgaCtrl.CursorPosition=3840;
}

void SystemCgaCharPut(U8 CharValue){
    if((CharValue>=0x20)&&(CharValue<=0x7e)){
         SystemCgaByteWrite(SystemCgaCtrl.CursorPosition++,CharValue);
         SystemCgaByteWrite(SystemCgaCtrl.CursorPosition++,SystemCgaCtrl.CharacterAttribute);
    }
    else{
         SystemCgaByteWrite(SystemCgaCtrl.CursorPosition++,'?');
         SystemCgaByteWrite(SystemCgaCtrl.CursorPosition++,SystemCgaCtrl.CharacterAttribute);
    }
    if(SystemCgaCtrl.CursorPosition==4000) SystemCgaScrollUp();
}

void SystemCgaScreenClean(void){
    U32 i;
    
    for(i=0;i<4000;i=i+2){
        SystemCgaByteWrite(i,' ');
        SystemCgaByteWrite(i+1,SystemCgaCtrl.CharacterAttribute);
    }
    SystemCgaCtrl.CursorPosition=0;
}

void SystemCgaChangeLine(void){
    U8 i;
    
    i=0;
    while(SystemCgaCtrl.CursorPosition>160){
        SystemCgaCtrl.CursorPosition=SystemCgaCtrl.CursorPosition-160;
        i++;    
    }
    SystemCgaCtrl.CursorPosition=(i+1)*160;
    if(SystemCgaCtrl.CursorPosition==4000) SystemCgaScrollUp(); 
}

void SystemCgaStringPrint(U8* pString){
    while(*pString!=0){
        if(*pString==0x0a) SystemCgaChangeLine();
        else if(*pString==0x0d); // 0x0a 0x0d is change line ,too.
        else SystemCgaCharPut(*pString);
        pString++;
    }
    SystemCgaCursorSet();
}

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