From ffe6eb09045d5e46810a80dda0a1fbd1693d73d4 Mon Sep 17 00:00:00 2001
From: Ain <41307858+nero@users.noreply.github.com>
Date: Sat, 31 Aug 2019 11:57:15 +0000
Subject: [PATCH] Add malloc_sector

---
 kernel/malloc.asm | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/kernel/malloc.asm b/kernel/malloc.asm
index 1fe4474..df634cf 100644
--- a/kernel/malloc.asm
+++ b/kernel/malloc.asm
@@ -86,11 +86,11 @@ malloc_dump:
   pop dx
   ret
 
-; allocate a 16 byte section
+; Allocate a paragraph
 ; out BX ptr
 malloc:
   ; search for a byte that is not 0xFF
-  mov di, 0x0600
+  call malloc_get_table
   mov cx, 0x0200
   mov al, 0xFF
   repe scasb
@@ -119,6 +119,7 @@ malloc:
   mov bx, di
   ret
 
+; Free a paragraph
 ; IN: 0:BX ptr to paragraph to be marked as free
 free:
   call malloc_calc_offsets
@@ -126,6 +127,31 @@ free:
   and byte [bx+di], al
   ret
 
+; Allocate a sector, 512 bytes or 32 paragraphs
+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
+
 fatal_oom:
   call printf
   db "PANIC OOM", 0x0A, 0x0D, 0x00