Refocus malloc on lisp node allocation, implement basic cons creation

cons.asm

@@ -0,0 +1,32 @@
+; All ptrs in ds segment, pointing to a node as returned by malloc
+
+; in	ax	ptr car
+;	bx	ptr cdr
+; out	di	ptr con
+cons:
+  push cx ; length for malloc
+  push dx
+  mov cx,4
+  mov dl,0x01 ; type for cons
+  call malloc
+  pop dx
+  pop cx
+  mov word [di+0x04],ax
+  mov word [di+0x06],bx
+  ret
+
+; in	ax	ptr con
+; out	di	ptr car
+car:
+  mov si,ax
+  ; TODO: type check
+  mov di,[si+0x04]
+  ret
+
+; in    ax   ptr con
+; out   di   ptr cdr
+cdr:
+  mov si,ax
+  ; TODO: type check
+  mov di,[si+0x06]
+  ret

heap.asm

@@ -2,7 +2,9 @@ verbose_malloc:
   call malloc
   push si ; both backup and input value for kprintf
   mov si,.fmt
+  push di
   call kprintf
+  pop di
   pop si
   ret
 .fmt:
@@ -11,42 +13,44 @@ verbose_malloc:
 ; Allocates memory on the kernel heap
 ; Strategy: smallest fit
 ; in	cx	size in bytes
-; out	si	pointer
+;       dl	node type
+; out	ds:di	pointer
 ;
 ; Header:
 ;	word	ptr to next item (this implies its size)
 ;	byte	00 = free, >0 used (refcount)
+;	byte	high-level type
 malloc:
   push ax
-  mov si,heap
+  push bx
+  mov di,heap
+  add cx, 0x04 ; header length
   jmp .check
 .next:
-  mov si,[si]
+  add di,[di]
 .check:
-  mov ax,[si]
+  mov ax,[di]
   test ax,0xFFFF
   jz .append ; we are on last entry
-  cmp byte [si+2],0x00
+  cmp byte [di+2],0x00
   jne .next ; entry is in use
   sub ax,cx
   je .reuse ; entry has exact length
   jc .next ; entry too short
   jmp .next ; we'd have to split, not implemented yet
 .reuse: ; exact length
-  mov byte [si+2],0xFF
+  mov byte [di+2],0xFF
   jmp .end
 .append: ; append to last item
-  mov ax, si
+  mov word [di], cx
-  add ax, 3
+  mov byte [di+2], 0x00
-  add ax, cx
+  mov byte [di+3], dl
-  mov word [si], ax
+  push di
-  mov byte [si+2], 0xFF
+  add word di, [di]
-  push si
+  mov byte [di],0x0000
-  mov word si,[si]
+  pop di
-  mov byte [si],0x0000
-  pop si
 .end:
-  add si, 0x03
+  pop bx
   pop ax
   ret
 

int.asm

@@ -0,0 +1,9 @@
+; Create a integer atom from a string describing said integer
+; in	ds:si	pointer to function arguments
+;	ds:di	pointer to integer atom
+int:
+  sub sp, 0x30
+  mov bp, sp ; buffer for integer
+
+  add sp, 0x30
+  ret

main.asm

@@ -48,10 +48,11 @@ main:
 
   call ivt_set
 
-  mov cx, 0x0010
+  mov ax, 0
-  call verbose_malloc
+  mov bx, 0
-  call verbose_malloc
+  call cons
-  call verbose_malloc
+  mov si, di
+  call print
 
   ret
 
@@ -60,5 +61,9 @@ main:
 %include "kprintf.asm"
 %include "heap.asm"
 
+%include "cons.asm"
+%include "int.asm"
+%include "print.asm"
+
 heap:
   dw 0

print.asm

@@ -0,0 +1,25 @@
+; dump contents of a node to screen
+; in	si
+print:
+  push si ; byte iterator
+  push cx ; position of next item
+  push ax ; al is byte value
+  mov word cx, [si] ; fetch position of next item
+  cmp cx, 0x40
+  jng .loop
+  mov cx, 0x40
+.loop:
+  lodsb
+  call kprint8
+  mov al, 0x20
+  call kputc
+  loopnz .loop
+
+  mov al, 0x0A
+  call kputc
+  mov al, 0x0D
+  call kputc
+  pop ax
+  pop cx
+  pop si
+  ret