From 72c6e9763ca61bc9d7de5f7080ee1c8a1c7c1562 Mon Sep 17 00:00:00 2001
From: Miguel <m.i@gmx.at>
Date: Tue, 21 Aug 2018 19:42:33 +0200
Subject: cleaning up a bit

---
 kernel/GDT.c | 136 -----------------------------------------------------------
 1 file changed, 136 deletions(-)
 delete mode 100644 kernel/GDT.c

(limited to 'kernel/GDT.c')

diff --git a/kernel/GDT.c b/kernel/GDT.c
deleted file mode 100644
index 4bc7ca2..0000000
--- a/kernel/GDT.c
+++ /dev/null
@@ -1,136 +0,0 @@
-// http://wiki.osdev.org/GDT_Tutorial
-#include "lib/logger/log.h"
-#include "usermode.h"
-#define FOOLOS_MODULE_NAME "GDT"
-
-#include <stdint.h>
-#define GDT_SIZE 6
-
-extern sys_tss;
-
-typedef struct GDT_struct
-{
-    uint32_t base;
-    uint32_t limit;
-    uint32_t type;
-
-}GDT;
-
-//alternative
-struct gdt_entry_bits
-{
-	unsigned int limit_low:16;
-	unsigned int base_low : 24;
-     //attribute byte split into bitfields
-	unsigned int accessed :1;
-	unsigned int read_write :1; //readable for code, writable for data
-	unsigned int conforming_expand_down :1; //conforming for code, expand down for data
-	unsigned int code :1; //1 for code, 0 for data
-	unsigned int always_1 :1; //should be 1 for everything but TSS and LDT
-	unsigned int DPL :2; //priveledge level
-	unsigned int present :1;
-     //and now into granularity
-	unsigned int limit_high :4;
-	unsigned int available :1;
-	unsigned int always_0 :1; //should always be 0
-	unsigned int big :1; //32bit opcodes for code, uint32_t stack for data
-	unsigned int gran :1; //1 to use 4k page addressing, 0 for byte addressing
-	unsigned int base_high :8;
-} __packed; //or __attribute__((packed))
-
-
-static GDT myGDT[GDT_SIZE];
-static uint8_t gdt_struct[GDT_SIZE*8];
-
-/**
- * \param target A pointer to the 8-byte GDT entry
- * \param source An arbitrary structure describing the GDT entry
- */
-void encodeGdtEntry(uint8_t *target, GDT source)
-{
-    // Check the limit to make sure that it can be encoded
-    if ((source.limit > 65536) && (source.limit & 0xFFF) != 0xFFF)
-    {
-	panic(FOOLOS_MODULE_NAME,"trying to set an invalid GDT source.limit!");
-    }
-    if (source.limit > 65536) {
-        // Adjust granularity if required
-        source.limit = source.limit >> 12;
-        target[6] = 0xC0;
-    } else {
-	target[6] = 0x40;
-    }
- 
-    // Encode the limit
-    target[0] = source.limit & 0xFF;
-    target[1] = (source.limit >> 8) & 0xFF;
- 
-    // 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;
-
-    target[5] = source.type;
-    target[6] |= (source.limit >> 16) & 0xF;
- 
-    // And... Type
-
-    /*
-
-0 1 dw 0xffff	    ;limit
-2 3 dw 0x0	    ;base
-4   db 0x0	    ;base
-5   db 10011010b    ;flags
-6   db 11001111b    ;flags & seg.limit
-7   db 0x0	    ;base
-    */
-
-
-}
-
-void gdt_setup()
-{
-    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"setting up Global Descriptor Table");
-    //selector 0x0
-    myGDT[0].base=0;
-    myGDT[0].limit=0;
-    myGDT[0].type=0;
-
-    //selector 0x8 code
-    myGDT[1].base=0;
-    myGDT[1].limit=0xffffffff;
-    myGDT[1].type=0x9a;
-
-    //selector 0x10 data
-    myGDT[2].base=0;
-    myGDT[2].limit=0xffffffff;
-    myGDT[2].type=0x92;
-
-    //selector 0x18 code user
-    myGDT[3].base=0;
-    myGDT[3].limit=0xffffffff;
-    myGDT[3].type=0xFa;
-
-    //selector 0x20 data user
-    myGDT[4].base=0;
-    myGDT[4].limit=0xffffffff;
-    myGDT[4].type=0xF2;
-
-    //TSS 0x28
-    myGDT[5].base=&sys_tss; //tss start?
-    myGDT[5].limit=sizeof(tss_struct); //tss end?
-    myGDT[5].type=0x89;
-
-
-    // transcript to format the processor wants
-    for(int i=0;i<GDT_SIZE;i++)
-        encodeGdtEntry(&gdt_struct[8*i],myGDT[i]);
-
-
-    // updat
-    install_tss();
-    setup_gdt(&gdt_struct[0],8*GDT_SIZE);
-
-
-}
-- 
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