Remove memory/mcb management

This commit is contained in:
Nero 2019-03-13 17:28:38 +00:00
parent b21acb076c
commit 56f01a0888
2 changed files with 7 additions and 245 deletions

View File

@ -3,15 +3,14 @@ cpu 8086
org 0x0100 org 0x0100
jmp main jmp main
str1:
db "Hello!", 0
main: main:
mov ax,0x1000 mov ax,cs
mov bx,0x0000 mov ds,ax
mov cx,0x0800 mov si,str1
call mtab_set call kprintf
call mtab_dump
ret ret
%include "kprintf.asm" %include "kprintf.asm"
; mem MUST be last because it will write after itself
%include "mem.asm"

237
mem.asm
View File

@ -1,237 +0,0 @@
; memory type is enum
; 00 - free
; 01 - unknown
; 02 - allocated by us
; 03 - reserved, like BIOS code or tables for the cpu
; 04 - unusable
; return the addr of the mtab
; out: es:bx
mtab_ref:
push cs
pop es
mov bx,mtab
ret
; finds a place for a new item in the mm table
; this detects 'empty' slots by the size field being zero
; in: ds:si: pointer to first mtab item
; out: bx: offset for empty slot
mtab_alloc:
push ax
call mtab_ref
.loop:
cmp WORD [es:bx],0x0000
je .end
add bx,0x0010
jmp .loop
.end:
pop ax
ret
; splits a mtab item at offset
; in: ds:si: pointer mtab item
; ax: split position in 16 byte blocks
; out: ds:si: pointer to lower half
; ds:di: pointer to upper half
mtab_split:
push cx ; remaining memory block length
mov cx,[ds:si]
mov [ds:si],ax ; this resizes the first item
sub cx, ax
push bx
call mtab_alloc
mov di,bx
pop bx
push si ; backup because movsw increments them
push di ; ^
push cx ; counter for movsb
mov es,ds
mov cx,0x08 ; 8 words = 16 bytes
rep movsw ; repeat cx times
pop cx
pop di
pop si
mov [ds:di],cx
pop cx
ret
; in: ax: segment
; bh: task id (0 for non-task memory)
; bl: memory type (see enum at top of file)
; cx: number of 16-byte blocks
mtab_set:
push ds
push cx ; length of current item
push dx ; cumulative position
push bx ; pointer to mtab item
call mtab_ref
mov dx,0x0000
push bx ; use as iterator, restoring base value afterwards
.findbase: ; we pick the mtab item where our segment lies in
mov cx,[es:bx]
add dx,cx
cmp dx,ax
jnbe .dupbase
add bx,0x0010
jmp .findbase
.dupbase: ; we duplicate it, so we potentially have one after and one before our new item
mov si,bx
call mtab_alloc
mov di,bx
pop bx
push si ; backup because movsw increments them
push di ; ^
push cx ; counter for movsb
mov cx,0x08 ; a mtab item is 8 words = 16 bytes
push es
pop ds
rep movsw
pop cx
pop di
pop si
.resizebase1:
push ax ; size = [Segment ax] - ([End addr dx] - [Length cx])
sub ax,dx
add ax,cx
mov [si],ax
pop ax
.resizebase2:
push dx
sub dx,ax
mov [di],dx
pop dx
.insert:
push bx
call mtab_alloc
mov dx,bx
pop bx
.base1_link:
push ax
mov ax,dx
sub ax,bx ; addr are relative to mtab start
mov [si+02],ax
pop ax
.new_link:
push ax
mov ax,di
sub ax,bx ; addr are relative to mtab start
mov di,dx
mov [di+02],ax
pop ax
pop bx
mov [di+04],bx
pop dx
pop cx
pop ds
ret
mtab_dump:
push cs
pop ds
mov cx,0x0000
mov bp,mtab
mov si,0x0000
.loop:
push si
mov ax, bp
add ax, si
add ax, 0x06
push ax
mov al,[bp+si+0x05]
push ax ; task id
mov al,[bp+si+0x04]
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
add cx,[bp+si+0x00]
mov ax,cx
dec ax
push ax ; end addr
push bx ; start addr
mov si,.linefmt
call kprintf
pop ax
pop ax
pop ax
pop ax
pop ax
pop si
; look for next line
mov ax,[bp+si+0x02]
test ax,0xFFFF
mov si,ax
jnz .loop
ret
.linefmt:
db "%X0 %XF %c %x %s", 0
.typechar:
db "F?ARU", 0
; pre-filled table for memory management
align 16
mtab:
; interrupt vector table
dw 0x0040
dw 0x0010
db 3
db 0
db "IVT", 0
align 16
; bios data area (writes here during runtime)
dw 0x0010
dw 0x0020
db 3
db 0
db "BDA", 0
align 16
dw 0x9FB0
dw 0x0030
db 0
db 0
db 0
align 16
dw 0x5000
dw 0x0040
db 4
db 0
db 0
align 16
dw 0x1000
dw 0x0000
db 4
db 0
db "BIOS ROM", 0
align 16
dw 0x0000
align 16
dw 0x0000
align 16
dw 0x0000
align 16
dw 0x0000