X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=3sys;a=blobdiff_plain;f=sys1%2Fkern%2Fsrc%2Fdesc.c;fp=sys1%2Fkern%2Fsrc%2Fdesc.c;h=d02c5fc2decbaa06fd6acae5660424d1fb3c7c1f;hp=0000000000000000000000000000000000000000;hb=0d2d1730817f3ef5fc766149f2598480094cbae8;hpb=6ccd3a47d05be145256a79a1de100f01ebd16a79

diff --git a/sys1/kern/src/desc.c b/sys1/kern/src/desc.c
new file mode 100644
index 0000000..d02c5fc
--- /dev/null
+++ b/sys1/kern/src/desc.c
@@ -0,0 +1,45 @@
+#include "desc.h"
+
+#define SEG_TYPE_SYSTEM	0
+#define SEG_TYPE_CODE	0x00001800
+#define SEG_TYPE_DATA	0x00001000
+#define SEG_TYPE_TSS	0x00000100
+#define SEG_TYPE_INTR	0x00000e00
+#define SEG_TYPE_TRAP	0x00000f00
+
+#define SEG_ACCESSED	0x00000100
+#define SEG_PRESENT		0x00008000
+#define SEG_AVL			0x00100000
+#define SEG_GRAN		0x00800000
+
+/* data segment type flags */
+#define SEG_WR			0x00000200
+#define SEG_EXPDN		0x00000400
+#define SEG_BIG			0x00400000
+/* code segment type flags */
+#define SEG_RD			0x00000200
+#define SEG_CONFORM		0x00000400
+#define SEG_DEF			0x00400000
+
+
+void desc_seg(struct desc *desc, int type, uint32_t base, uint32_t limit, int dpl)
+{
+	if(type == SEG_NULL) {
+		desc->d[0] = desc->d[1] = 0;
+		return;
+	}
+
+	desc->d[0] = (limit & 0xffff) | (base << 16);
+	desc->d[1] = ((base >> 16) & 0xff) | (type << 8) | SEG_PRESENT | (dpl << 13);
+	desc->d[1] |= (base & 0xff000000) | (limit & 0xf0000) | SEG_AVL | SEG_GRAN;
+
+	switch(type) {
+	case SEG_CODE:
+		desc->d[1] |= (3 << 11) | SEG_DEF | SEG_RD;
+		break;
+
+	case SEG_DATA:
+		desc->d[1] |= (2 << 11) | SEG_WR;
+		break;
+	}
+}