os/kernel32/src/main.c at main · reindeer002/os · GitHub

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//
// Created by reindeer002-laptop on 3/12/26.
//

#include "types.h"
#include "page.h"
#include "mode-switch.h"

void kPrintString(int iX, int iY, const char* pcString);
BOOL kInitializeKernel64Area();
BOOL kIsMemoryEnough();
void kCopyKernel64ImageTo2Mbyte();

void main() {
    DWORD dwEAX, dwEBX, dwECX, dwEDX;
    char vcVendorString[13] = { 0 };

    kPrintString(0, 3, "Protected Mode C Language Kernel Start.");

    kPrintString(0, 3, "C Language Kernel Started.");
    kPrintString(0, 4, "Minimum Memory Size Check.");
    if(kIsMemoryEnough() == FALSE) {
        kPrintString(45, 4, "FAIL");
        kPrintString(0, 5, "Not Enough Memory, REIN OS Requires Over 64MB Memory.");
        while(1);
    }
    kPrintString(45, 4, "PASS");

    kPrintString(0, 5, "IA-32e Kernel Area Initialize.");
    if(kInitializeKernel64Area() == FALSE) {
        kPrintString(45, 5, "FAIL");
        kPrintString(0, 6, "Kernel Area Initialization Fail.");
        while(1);
    }
    kPrintString(45, 5, "PASS");

    kPrintString(0, 6, "IA-32e Page Tables Initialize.");
    kInitializePageTables();
    kPrintString(45, 6, "PASS");

    kReadCPUID(0, &dwEAX, &dwEBX, &dwECX, &dwEDX);
    *(DWORD*) vcVendorString = dwEBX;
    *((DWORD*)vcVendorString + 1) = dwEDX;
    *((DWORD*)vcVendorString + 2) = dwECX;
    kPrintString(0, 7, "CPU Vendor String : ");
    kPrintString(45, 7, vcVendorString);

    kReadCPUID(0x80000001, &dwEAX, &dwEBX, &dwECX, &dwEDX);
    kPrintString(0, 8, "64bit Mode Support Check : ");
    if(dwEDX & ( 1 << 29 )) {
        kPrintString(45, 8, "PASS");
    } else {
        kPrintString(45, 8, "FAIL");
        kPrintString(0, 9, "64bit Mode Not Supported.");
        while(1);
    }

    kPrintString(0, 9, "Copy IA-32e Kernel To 2M Address.");
    kCopyKernel64ImageTo2Mbyte();
    kPrintString(45, 9, "PASS");

    kPrintString(0, 10, "Switch To IA-32e Mode");
    kSwitchAndExecute64bitKernel();

    while(1);
}

void kPrintString(int iX, int iY, const char* pcString) {
    CHARACTER* pstScreen = ( CHARACTER* ) 0xB8000;

    pstScreen += ( iY * 80 ) + iX;
    for(int i = 0; pcString[i] != 0; i++) {
        pstScreen[i].bCharacter = pcString[i];
    }
}

BOOL kInitializeKernel64Area() {
    DWORD* pdwCurrentAddress;

    pdwCurrentAddress = ( DWORD* ) 0x100000;

    while((DWORD) pdwCurrentAddress < 0x600000) {
        *pdwCurrentAddress = 0x00;
        if(*pdwCurrentAddress != 0) {
            return FALSE;
        }
        pdwCurrentAddress++;
    }
    return TRUE;
}

BOOL kIsMemoryEnough() {
    DWORD* pdwCurrentAddress;
    pdwCurrentAddress = (DWORD*) 0x100000;
    while((DWORD)pdwCurrentAddress < 0x4000000) {
        *pdwCurrentAddress = 0x12345678;

        if(*pdwCurrentAddress != 0x12345678) {
            return FALSE;
        }
        pdwCurrentAddress += (0x100000 / 4);
    }
    return TRUE;
}

void kCopyKernel64ImageTo2Mbyte() {
    WORD wKernel32SectorCount, wTotalKernelSectorCount;
    DWORD *pdwSourceAddress, *pdwDestinationAddress;

    wTotalKernelSectorCount = *((WORD*) 0x7C05);
    wKernel32SectorCount = *((WORD*) 0x7C07);

    pdwSourceAddress = (DWORD*) (0x10000 + (wKernel32SectorCount * 512));
    pdwDestinationAddress = (DWORD*) 0x200000;
    for(int i = 0; i < (wTotalKernelSectorCount - wKernel32SectorCount) * 512 / 4; i++) {
        *pdwDestinationAddress = *pdwSourceAddress;
        pdwDestinationAddress++;
        pdwSourceAddress++;
    }
}