WIP

mem.asm

@@ -1,19 +1,77 @@
-; converts a memory block type code into char representation
-; in: al
-; out: al
-; destroys ah
-mm_type:
-  push bp
-  push si
-  mov bp,.typechar
-  and ax,0x00FF
-  mov si,ax
-  mov al,[bp+si]
-  pop si
-  pop bp
+; memory type is enum
+;  00 - free
+;  01 - unknown
+;  02 - allocated by us
+;  03 - reserved, like BIOS code or tables for the cpu
+;  04 - unusable
+
+; search memory table for a item matching a segment addr
+; in:  ax: segment
+; out: bp: table start address
+;      si: table item offset
+;      ax: offset from begin of memory block
+mm_findtab:
+  push bx
+  push cx
+  push cs
+  pop ds
+  mov cx,0x0000
+  mov bp,memtab
+  mov si,0x0000
+.loop:
+  add cx,[bp+si+0x00]
+  cmp cx,ax
+  jnbe .end
+  mov bx,[bp+si+0x02]
+  mov si,bx
+  jmp .loop
+.end:
+  sub cx,[bp+si+0x00]
+  sub ax,cx
+  pop cx
+  pop bx
+  ret
+
+; finds a place for a new item in the mm table
+; out: si
+mm_taballoc:
+  push ax
+  mov bp,memtab
+  mov si,0x0000
+.loop:
+  cmp WORD [bp+si],0x0000
+  je .end
+  mov ax,si
+  add ax,0x0010
+  mov si,ax
+  jmp .loop
+.end:
+  pop ax
+  ret
+
+; force-sets the type of a memory block (dangerous)
+; in:  ax: segment
+;      bl: memory type
+;      cx: length in 16 byte blocks
+mm_setup_range:
+  push dx
+  call mm_findtab ; i'll refer the item returned in si as 'base'
+  mov dx,[bp+si] ; get size from base
+  push si
+  ; duplicate the base
+  call mm_taballoc
+  mov di,si
+  pop si
+
+  push ds
+  pop es
+  push cx
+  mov cx,0x0010
+  rep movsb ; copies 0x10 bytes from ES:SI to DS:DI
+  pop cx
+
+  pop dx
   ret
-.typechar:
-  db "F?ARU", 0
 
 mm_print:
   push cs
@@ -34,7 +92,14 @@ mm_print:
   push ax ; task id
 
   mov al,[bp+si+0x04]
-  call mm_type
+  push bp
+  push si
+  mov bp,.typechar
+  and ax,0x00FF
+  mov si,ax
+  mov al,[bp+si]
+  pop si
+  pop bp
   push ax ; memory type
 
   mov bx,cx
@@ -62,6 +127,8 @@ mm_print:
   ret
 .linefmt:
   db "%X0 %XF %c %x %s", 0
+.typechar:
+  db "F?ARU", 0
 
 ; pre-filled table for memory management
 align 16
@@ -78,28 +145,30 @@ align 16
   dw 0x0020
   db 3
   db 0
-  db "BIOS DATA", 0
+  db "BDA", 0
 align 16
   dw 0x9FB0
   dw 0x0030
-  db 1
+  db 0
   db 0
   db 0
 align 16
-  dw 0x2000
+  dw 0x5000
   dw 0x0040
   db 4
   db 0
-  db "I/O BUS", 0
-align 16
-  dw 0x3000
-  dw 0x0050
-  db 4
   db 0
-  db "BIOS EXT", 0
 align 16
   dw 0x1000
   dw 0x0000
   db 4
   db 0
-  db "BIOS", 0
+  db "BIOS ROM", 0
+align 16
+  dw 0x0000
+align 16
+  dw 0x0000
+align 16
+  dw 0x0000
+align 16
+  dw 0x0000