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authorLoic Guegan <manzerbredes@mailbox.org>2021-04-12 10:13:21 +0200
committerLoic Guegan <manzerbredes@mailbox.org>2021-04-12 10:13:21 +0200
commit39713a3736145483dd3310c3605f940ca34f05c3 (patch)
treed4dcdf0f3b667a5d706aa4b04501a71facf186bd /src/utils/gdt.c
parent6edeba8fe208fb019aec00fdc72b97407a8078d3 (diff)
Refactoring
Diffstat (limited to 'src/utils/gdt.c')
-rw-r--r--src/utils/gdt.c98
1 files changed, 0 insertions, 98 deletions
diff --git a/src/utils/gdt.c b/src/utils/gdt.c
deleted file mode 100644
index 8c1c70d..0000000
--- a/src/utils/gdt.c
+++ /dev/null
@@ -1,98 +0,0 @@
-#include "gdt.h"
-#include "mem.h"
-
-struct GDT_REGISTER GDTR = { 0, 0 };
-GDT_TSS TSS;
-
-void gdt_memcpy(){
- GDTR.limit=8*GDT_MAX_ENTRIES; // Each entry is 8 bytes and 8 entries
- GDTR.base=0x800;
- gdt_write_entry((GDT_ENTRY){0,0,0,0},0); // First one must be null
-
- // ----- Kernel Segments
- GDT_ENTRY cs_desc;
- cs_desc.base=0;
- cs_desc.limit=0xFFFFF;
- cs_desc.flags=GDT_SZ|GDT_GR;
- cs_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_EXEC|GDT_RW;
-
- GDT_ENTRY ds_desc;
- ds_desc.base=0;
- ds_desc.limit=0xFFFFF;
- ds_desc.flags=GDT_SZ|GDT_GR;
- ds_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_RW;
-
- GDT_ENTRY ss_desc;
- ss_desc.base=0;
- ss_desc.limit=0;
- ss_desc.flags=GDT_SZ|GDT_GR;
- ss_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_RW|GDT_DC;
-
- // Write GDT descriptors into memory
- gdt_write_entry(cs_desc, 1);
- gdt_write_entry(ds_desc, 2);
- gdt_write_entry(ss_desc, 3);
-
- // ----- User Segments
- GDT_ENTRY ucs_desc;
- ucs_desc.base=0; // With paging will take care of allocating the right address for each task
- ucs_desc.limit=0xFFFFF;
- ucs_desc.flags=GDT_SZ|GDT_GR;
- ucs_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_EXEC|GDT_RW|GDT_DC;
-
- GDT_ENTRY uds_desc;
- uds_desc.base=0;
- uds_desc.limit=0xFFFFF;
- uds_desc.flags=GDT_SZ|GDT_GR;
- uds_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_RW;
-
- GDT_ENTRY uss_desc;
- uss_desc.base=0; // Not used in stack descriptor
- uss_desc.limit=0x64; // Define how much entry it can contains
- uss_desc.flags=GDT_SZ|GDT_GR;
- uss_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_RW|GDT_DC;
-
- // Write GDT descriptors into memory
- gdt_write_entry(ucs_desc, 4); // Each entry is 64 bits (8 bytes)
- gdt_write_entry(uds_desc, 5);
- gdt_write_entry(uss_desc, 6);
-
- // Init TSS segment
- TSS.t_reserved=0;
- TSS.io_map=0;
-
- GDT_ENTRY tss_desc;
- tss_desc.base=(u32)&TSS; // Not used in stack descriptor
- tss_desc.limit=0x68; // Define how much bytes it occupies
- tss_desc.flags=0;
- tss_desc.access=0x89 | GDT_PRVL_3; // Note that 0x89 is specific to TSS!
- gdt_write_entry(tss_desc, 7);
-
-}
-
-void gdt_write_entry(GDT_ENTRY entry, u32 id){
- int descriptor[2];
-
- // First row of the descriptor
- descriptor[0]=(entry.limit & 0xFFFF)|(entry.base << 16);
-
- // Format second row of the descriptor
- u16 base=(entry.base >> 16) & 0xFF;
- u16 access=entry.access & 0xFF;
- u16 limit=(entry.limit >> 16) & 0xF; // Remember: limits it is on 20 bits so 4 last bits
- u8 flags=entry.flags & 0xF;
- u8 base2=entry.base >> 24; // Take the last 8 bits
- descriptor[1]=base|access<<8|limit<<16|flags<<20|base2<<24;
-
- // Copy descriptor into memory
- memcpy(descriptor,(void*)GDTR.base+8*id,8); // Each entry is 64 bits (8 bytes)
-}
-
-int gdt_user_ds_base(){
- char *addr=(char*)GDTR.base+48;
- int *base0_15=(int*)addr+2;
- int *base16_31=(int*)addr+7;
- int base0_15_content=*base0_15 & 0xFFFF;
- int base16_21_content=*base16_31 & 0xFFFF;
- return(base16_21_content<<16 & base0_15_content);
-} \ No newline at end of file