Update shell.asm

[BOS.git] / kernel / int / idt.asm

diff --git a/kernel/int/idt.asm b/kernel/int/idt.asm
index 5b4a8d8a3942b843e50b44ad86fe1aa990fcd343..c6b28417e5f84963be8440b0db960d04dbb04849 100644 (file)
--- a/kernel/int/idt.asm
+++ b/kernel/int/idt.asm
@@ -1,11 +1,25 @@
 ;----------------------------------------------------------;\r
-; BOS kernel                Christoffer Bubach, 2003-2005. ;\r
+; BOS kernel                Christoffer Bubach, 2003-2015. ;\r
 ;----------------------------------------------------------;\r
 ;                                                          ;\r
-;    set/modify IDT entries                                ;\r
+;   Set/modify IDT entries                                 ;\r
 ;                                                          ;\r
 ;----------------------------------------------------------;\r
 \r
+;-----------------------------------------------------;\r
+;                                                     ;\r
+; IDT entry structure                                 ;\r
+;                                                     ;\r
+;   16bit - entry offset bits 0..15                   ;\r
+;   16bit - code segment selector in GDT or LDT       ;\r
+;   8bit  - unused, set to 0                          ;\r
+;   8bit  - type and attributes                       ;\r
+;              -  0xE = 32bit intterrupt              ;\r
+;              -  0x8 = Present bit = 1               ;\r
+;   16bit - entry offset bits 16..31                  ;\r
+;                                                     ;\r
+;   middle section for code segment 08 = 0x8E000008   ;\r
+;-----------------------------------------------------;\r
 \r
 \r
 ;--------------------------------------------------;\r
@@ -15,24 +29,29 @@
 init_idt:\r
         push   eax\r
         push   ecx\r
+        push   edi\r
 \r
+        xor    edi, edi\r
         xor    ecx, ecx\r
-    .l1:\r
-        mov    eax, esi                               ; loop full IDT and\r
-        mov    [(0x6c00+ecx)], ax                     ; set to one ISR\r
-        add    ecx, 2\r
+        add    edi, [idtr.address]\r
+    .l1:                                              ; loop full IDT table\r
+        mov    eax, esi\r
+        mov    word [edi], ax                         ; set handler lower offset\r
+        add    edi, 2\r
 \r
-        mov    dword [(0x6c00+ecx)], 0x8E000008       ; 0x6c00 is where\r
-        add    ecx, 4                                 ; we put the IDT\r
+        mov    dword [edi], 0x8E000008                ; set IDT segment and attributes\r
+        add    edi, 4\r
 \r
         mov    eax, esi\r
         shr    eax, 16\r
-        mov    [(0x6c00+ecx)], ax\r
-        add    ecx, 2\r
+        mov    word [edi], ax                         ; set handler high offset\r
+        add    edi, 2\r
 \r
-        cmp    ecx, 0x800                             ; 256 ints\r
-        jb     .l1                                    ; * 8 bytes each\r
+        add    cx, 8                                  ; 8byte *\r
+        cmp    cx, word [idtr.size]                   ; 256 ints\r
+        jb     .l1                                    ; = done?\r
 \r
+        pop    edi\r
         pop    ecx\r
         pop    eax\r
         ret\r
@@ -45,30 +64,30 @@ init_idt:
 ;      edi = int function pointer      ;\r
 ;--------------------------------------;\r
 set_int:\r
-               push   eax\r
-               push   ecx\r
+        push   eax\r
+        push   ecx\r
 \r
-               mov    al, 8                                  ; 8 bytes for each int\r
-               mul    cl                                     ; cl * al = ax\r
-               movzx  ecx, ax                                ; ecx = IDT offset\r
-               shr    ecx, 1                                 ; 1/2 for dword list\r
-               mov    dword [(idt_list+ecx)], edi            ; add to dword int list\r
-               movzx  ecx, ax                                ; ecx = IDT offset\r
+        mov    al, 8                                  ; 8 bytes for each int\r
+        mul    cl                                     ; cl * al = ax\r
+        movzx  ecx, ax                                ; ecx = IDT offset\r
+        shr    ecx, 1                                 ; 1/2 for dword list\r
+        mov    dword [(idt_list+ecx)], edi            ; add to dword int list\r
+        movzx  ecx, ax                                ; ecx = IDT offset\r
 \r
-               mov    eax, edi\r
-               mov    [(0x6c00+ecx)], ax\r
-               add    ecx, 2\r
+        mov    eax, edi\r
+        mov    [(0x6c00+ecx)], ax\r
+        add    ecx, 2\r
 \r
-               mov    dword [(0x6c00+ecx)], 0x8E000008\r
-               add    ecx, 4\r
+        mov    dword [(0x6c00+ecx)], 0x8E000008\r
+        add    ecx, 4\r
 \r
-               mov    eax, edi\r
-               shr    eax, 16\r
-               mov    [(0x6c00+ecx)], ax\r
+        mov    eax, edi\r
+        shr    eax, 16\r
+        mov    [(0x6c00+ecx)], ax\r
 \r
-               pop    ecx\r
-               pop    eax\r
-               ret\r
+        pop    ecx\r
+        pop    eax\r
+        ret\r
 \r
 \r
 \r
@@ -78,15 +97,15 @@ set_int:
 ;      out: esi = address or 0 if none present   ;\r
 ;------------------------------------------------;\r
 get_int:\r
-               push   eax\r
+        push   eax\r
 \r
-               mov    eax, 4                                 ; 4 bytes for each address\r
-               mul    cl                                     ; cl * al = ax\r
-               mov    esi, idt_list\r
-               add    esi, eax\r
+        mov    eax, 4                                 ; 4 bytes for each address\r
+        mul    cl                                     ; cl * al = ax\r
+        mov    esi, idt_list\r
+        add    esi, eax\r
 \r
-               pop    eax\r
-               ret\r
+        pop    eax\r
+        ret\r
 \r
 \r
 \r
@@ -96,24 +115,24 @@ get_int:
 ;      in:  esi = pointer to int list    ;\r
 ;----------------------------------------;\r
 set_idt_list:\r
-               push   eax\r
-               push   edi\r
-\r
-               xor    ecx, ecx\r
-       .l1:\r
-               lodsd\r
-               or     eax, eax\r
-               jz     .next\r
-               mov    edi, eax\r
-               call   set_int\r
-       .next:\r
-               inc    ecx\r
-               cmp    ecx, 0x100\r
-               jb     .l1\r
-\r
-               pop    edi\r
-               pop    eax\r
-               ret\r
+        push   eax\r
+        push   edi\r
+\r
+        xor    ecx, ecx\r
+    .l1:\r
+        lodsd\r
+        or     eax, eax\r
+        jz     .next\r
+        mov    edi, eax\r
+        call   set_int\r
+    .next:\r
+        inc    ecx\r
+        cmp    ecx, 0x100\r
+        jb     .l1\r
+\r
+        pop    edi\r
+        pop    eax\r
+        ret\r
 \r
 \r
 \r