diff --git a/kernel/main.asm b/kernel/main.asm index 9f21611..c3c6da9 100644 --- a/kernel/main.asm +++ b/kernel/main.asm @@ -73,15 +73,11 @@ start: xor ax, ax mov ds, ax mov es, ax - ; setup code + data stack mov ss, ax - mov sp, ax - mov bp, sp + mov sp, 0x800 + mov di, sp call announce - call malloc_reset - - call malloc_dump cli .halt: @@ -91,13 +87,9 @@ start: %include "printf.inc" %include "print.asm" -%include "popcnt.asm" - %include "intr.asm" %include "debug.asm" -%include "malloc.asm" - times 512 nop align 512 diff --git a/kernel/malloc.asm b/kernel/malloc.asm deleted file mode 100644 index f451c1c..0000000 --- a/kernel/malloc.asm +++ /dev/null @@ -1,172 +0,0 @@ -; All these functions assume DS=0 and ES=0 - -malloc_reserve: - push bx - call malloc_mark_allocated - pop bx - add bx, 0x10 - loop malloc_reserve - ret - -malloc_reset: - xor ax, ax - mov es, ax - call malloc_get_table - mov cx, 0x100 ; 256 words - rep stosw - - ; reserve IVT and BDA, the extra data area and this table itself - xor bx, bx - mov cx, 0x80 - call malloc_reserve - - ; reserve location for chainloaded boot sector - mov bx, 0x7C00 - mov cx, 0x20 - call malloc_reserve - ret - -; Input: -; 0:BX - ptr to mem paragraph -; Output: -; AL - bitmask for byte in table -; BX - offset in table -malloc_calc_offsets: - ; ch is bit offset - ; cl is operand for bit shifts - push cx - - ; strip last 4 bits (offset within paragraph) - mov cl, 4 - shr bx, cl - - ; backup the next 3 bits of bx (wll be bit offset) - mov ch, bl - and ch, 0x07 - - ; calculate byte offset by shifting off 3 bits - mov cl, 3 - shr bx, cl - - ; setup bit mask in al, shifted by bit offset - mov al, 0x01 - mov cl, ch - shl al, cl - - pop cx - ; fallthrough to setup DI - -malloc_get_table: - mov di, 0x0600 - ret - -; IN: 0:BX ptr to paragraph to be marked as allocated -malloc_mark_allocated: - call malloc_calc_offsets - or byte [bx+di], al - ret - -malloc_dump: - call malloc_get_table - mov si, di - mov cx, 0x200 - xor dx, dx -.loop: - lodsb - call print8 - xor ah, ah - call popcnt - add dx, ax - loop .loop - mov cl, 6 - shr dx, cl - push dx - call printf - db " data %UkB", 0x0A, 0x0D, 0x00 - pop dx - ret - -; Allocate a paragraph -; out BX ptr -malloc: - ; search for a byte that is not 0xFF - call malloc_get_table - mov cx, 0x0200 - mov al, 0xFF - repe scasb - je fatal_oom - dec di - mov al, [es:di] - - sub di, 0x0600 - mov cl, 3 - shl di, cl - jmp .ishere - - ; advance one bit each time -.nextbit: - inc di - shr al, 1 -.ishere: - test al, 1 - jnz .nextbit - - mov cl, 4 - shl di, cl - - mov bx, di - call malloc_mark_allocated - mov bx, di - ret - -; Free a paragraph -; IN: 0:BX ptr to paragraph to be marked as free -free: - call malloc_calc_offsets - not al - and byte [bx+di], al - ret - -; Allocate a sector, 512 bytes or 32 paragraphs -; OUT BX ptr to sector -malloc_sector: - call malloc_get_table - mov cx, 0x0200 - xor ax, ax -.continue: - repne scasw - jne fatal_oom - - ; we need a second word to be 0, otherwise continue search - scasw - jne .continue - - sub di, 4 - not ax - stosw - stosw - - sub di, 0x604 - mov cl, 7 - shl di, cl - - xchg bx, di - ret - -; Free a sector -; IN BX ptr to sector -free_sector: - call malloc_calc_offsets - xor ax, ax - add di, bx - stosw - stosw - ret - -fatal_oom: - call printf - db "PANIC OOM", 0x0A, 0x0D, 0x00 - clip -.loop: - hlt - jmp .loop