# HG changeset patch
# User John Tsiombikas <nuclear@siggraph.org>
# Date 1303509078 -10800
# Node ID 8ea6debe42656d1dfe1e6daec19ccf511efab047
# Parent  9939a6d7a45a1ea08d4094cffa302a1890c726d8
starting on the task switching implementation

diff -r 9939a6d7a45a -r 8ea6debe4265 src/intr.c
--- a/src/intr.c	Wed Apr 06 07:42:44 2011 +0300
+++ b/src/intr.c	Sat Apr 23 00:51:18 2011 +0300
@@ -159,7 +159,7 @@
 	desc->d[3] = (addr & 0xffff0000) >> 16;
 }
 
-#define IS_TRAP(n)	((n) < 32)
+#define IS_TRAP(n)	((n) >= 32 && !IS_IRQ(n))
 static void set_intr_entry(int num, void (*handler)(void))
 {
 	int type = IS_TRAP(num) ? GATE_TRAP : GATE_INTR;
diff -r 9939a6d7a45a -r 8ea6debe4265 src/proc.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/proc.h	Sat Apr 23 00:51:18 2011 +0300
@@ -0,0 +1,14 @@
+#ifndef PROC_H_
+#define PROC_H_
+
+#include "tss.h"
+
+struct process {
+	int id;
+
+	struct task_state tss;
+
+	struct process *next;
+};
+
+#endif	/* PROC_H_ */
diff -r 9939a6d7a45a -r 8ea6debe4265 src/segm.c
--- a/src/segm.c	Wed Apr 06 07:42:44 2011 +0300
+++ b/src/segm.c	Sat Apr 23 00:51:18 2011 +0300
@@ -11,6 +11,8 @@
 #define BIT_CODE		(1 << 11)
 #define BIT_NOSYS		(1 << 12)
 #define BIT_PRESENT		(1 << 15)
+/* TSS busy bit */
+#define BIT_BUSY		(1 << 9)
 
 /* bits for the last 16bit part of the descriptor */
 #define BIT_BIG			(1 << 6)
@@ -19,7 +21,11 @@
 
 enum {TYPE_DATA, TYPE_CODE};
 
+#define TSS_TYPE_BITS	0x900
+#define TSS_BUSY		BIT_BUSY
+
 static void segm_desc(desc_t *desc, uint32_t base, uint32_t limit, int dpl, int type);
+static void task_desc(desc_t *desc, uint32_t base, uint32_t limit, int dpl, unsigned int busy);
 
 /* these functions are implemented in segm-asm.S */
 void setup_selectors(uint16_t code, uint16_t data);
@@ -27,7 +33,7 @@
 
 
 /* our global descriptor table */
-static desc_t gdt[3];
+static desc_t gdt[6];
 
 
 void init_segm(void)
@@ -35,6 +41,9 @@
 	memset(gdt, 0, sizeof gdt);
 	segm_desc(gdt + SEGM_KCODE, 0, 0xffffffff, 0, TYPE_CODE);
 	segm_desc(gdt + SEGM_KDATA, 0, 0xffffffff, 0, TYPE_DATA);
+	segm_desc(gdt + SEGM_UCODE, 0, 0xffffffff, 3, TYPE_CODE);
+	segm_desc(gdt + SEGM_UDATA, 0, 0xffffffff, 3, TYPE_DATA);
+	/*task_desc(gdt + SEGM_TASK, 0, 0xffffffff, 3, TSS_BUSY);*/
 
 	set_gdt((uint32_t)gdt, sizeof gdt - 1);
 
@@ -64,3 +73,13 @@
 	 */
 	desc->d[3] = ((limit >> 16) & 0xf) | ((base >> 16) & 0xff00) | BIT_GRAN | BIT_BIG;
 }
+
+static void task_desc(desc_t *desc, uint32_t base, uint32_t limit, int dpl, unsigned int busy)
+{
+	desc->d[0] = limit & 0xffff;
+	desc->d[1] = base & 0xffff;
+
+	desc->d[2] = ((base >> 16) & 0xff) | ((dpl & 3) << 13) | BIT_PRESENT |
+		TSS_TYPE_BITS | busy;
+	desc->d[3] = ((limit >> 16) & 0xf) | ((base >> 16) & 0xff00) | BIT_GRAN;
+}
diff -r 9939a6d7a45a -r 8ea6debe4265 src/segm.h
--- a/src/segm.h	Wed Apr 06 07:42:44 2011 +0300
+++ b/src/segm.h	Sat Apr 23 00:51:18 2011 +0300
@@ -3,6 +3,9 @@
 
 #define SEGM_KCODE	1
 #define SEGM_KDATA	2
+#define SEGM_UCODE	3
+#define SEGM_UDATA	4
+#define SEGM_TASK	5
 
 void init_segm(void);
 
diff -r 9939a6d7a45a -r 8ea6debe4265 src/tss.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/tss.h	Sat Apr 23 00:51:18 2011 +0300
@@ -0,0 +1,21 @@
+#ifndef TSS_H_
+#define TSS_H_
+
+#include <inttypes.h>
+
+struct task_state {
+	uint32_t prev_task;
+	uint32_t esp0, ss0;
+	uint32_t esp1, ss1;
+	uint32_t esp2, ss2;
+	uint32_t cr3;
+	uint32_t eip;
+	uint32_t eflags;
+	uint32_t eax, ecx, edx, ebx;
+	uint32_t esp, ebp, esi, edi;
+	uint32_t es, cs, ss, ds, fs, gs;
+	uint32_t ldt_sel;
+	uint16_t trap, iomap_addr;
+} __attribute__((packed));
+
+#endif	/* TSS_H_ */