diff options
Diffstat (limited to 'kernel/arch/x86/gdt2.cpp')
| -rw-r--r-- | kernel/arch/x86/gdt2.cpp | 51 | 
1 files changed, 51 insertions, 0 deletions
| diff --git a/kernel/arch/x86/gdt2.cpp b/kernel/arch/x86/gdt2.cpp new file mode 100644 index 0000000..0acdb0e --- /dev/null +++ b/kernel/arch/x86/gdt2.cpp @@ -0,0 +1,51 @@ +#include <stdio.h>
 +#include <stdint.h>
 +/*
 +// structure to be encoded at encodeGdtEntry()
 +struct GDT
 +{
 +    uint32_t base;
 +    uint32_t limit;
 +    uint8_t access_byte;
 +    uint8_t flags;
 +};
 +
 +GDT strnulldesc {0, 0, 0, 0};
 +GDT strkernelcode {0, 0xFFFFF, 0x9A, 0xC};
 +GDT strkerneldata {0, 0xFFFFF, 0x92, 0xC};
 +GDT strusercode {0, 0xFFFFF, 0xFA, 0xC};
 +GDT struserdata {0, 0xFFFFF, 0xF2, 0xC};
 +
 +uint8_t* nulldesc;
 +uint8_t* kernelcode;
 +uint8_t* kerneldata;
 +uint8_t* usercode;
 +uint8_t* userdata;
 +
 +
 +void encodeGdtEntry(uint8_t *target, struct GDT source)
 +{
 +    // Check the limit to make sure that it can be encoded
 +    if (source.limit > 0xFFFFF) {printf("GDT cannot encode limits larger than 0xFFFFF\n");}
 + 
 +    // Encode the limit
 +    target[0] = source.limit & 0xFF;
 +    target[1] = (source.limit >> 8) & 0xFF;
 +    target[6] = (source.limit >> 16) & 0x0F;
 + 
 +    // Encode the base
 +    target[2] = source.base & 0xFF;
 +    target[3] = (source.base >> 8) & 0xFF;
 +    target[4] = (source.base >> 16) & 0xFF;
 +    target[7] = (source.base >> 24) & 0xFF;
 + 
 +    // Encode the access byte
 +    target[5] = source.access_byte;
 + 
 +    // Encode the flags
 +    target[6] |= (source.flags << 4);
 +}
 +
 +extern "C" void setupGdt() {
 +
 +} */
\ No newline at end of file | 
