From 5b0f04f0c5d406def1acbcdbcc114e9b4bf5c7da Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Sun, 14 Jul 2024 10:52:51 -0700
Subject: Double Linked List

---
 linked_list.inc | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 main.asm        | 43 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/linked_list.inc b/linked_list.inc
index 4fbb923..0e5042b 100644
--- a/linked_list.inc
+++ b/linked_list.inc
@@ -20,19 +20,62 @@ endstruc
 	mov	qword [rax + ll_next],	0
 %endmacro
 
-%macro	dlln_alloc	0
+%macro	dll_alloc	0
 	alloc	DoublyLinkedListNode_size
 	mov	qword [rax + dll_next],	0
+	mov	qword [rax + dll_prev],	0
 %endmacro
 
 %macro	lln_free	0-1	rax
 	free	%1,	LinkedListNode_size
 %endmacro
 
-%macro	dlln_free	0-1	rax
+%macro	dll_free	0-1	rax
 	free	%1,	DoublyLinkedListNode_size
 %endmacro
 
+%macro	ll_seek	0-1	rax
+	mov	rax,	[%1 + ll_next]
+%endm
+
+_dll_seek_backward:
+	mov	rax,	[rax + dll_prev]
+	ret
+
+_dll_seek_forward:
+	mov	rax,	[rax + dll_next]
+	ret
+
+%macro	dll_seek	0-2	rax,"forward"
+%if "%1" != "%rax"
+	mov	rax,	%1
+%endif
+%if %2 == "forward"
+	call _dll_seek_forward
+%elif %2 == "backward"
+	call _dll_seek_backward
+%else
+	%error "Direction not specified!"
+%endif
+%endm
+
+_dll_end:
+.loop:
+	mov	rcx,	[rax + dll_next]
+	cmp	rcx,	0
+	je	.end
+	call	_dll_seek_forward
+	jmp	.loop
+.end:
+	ret
+
+%macro	dll_end	0-1	rax
+%if "%1" != "rax"
+	mov	rax,	%1
+%endif
+	call	_dll_end
+%endm
+
 %macro	ll_push	2
 	;; %1 = Current Linked List Node
 	;; %2 = Value to push (Must fit in a register, larger must be pushed as pointer to the underlying structure)
@@ -41,4 +84,19 @@ endstruc
 	mov	qword [rax + ll_value],	%2
 %endm
 
+%macro	dll_push	2
+	;; %1 = Current Doubly Linked List Node
+	;; %2 = Value to push (Must fit in a register, larger must be pushed as pointer to the underlying structure)
+	dll_alloc
+	mov	rcx,	[%1 + dll_next]
+	cmp	rcx,	0
+	je	%%skip
+	mov	qword [rcx + dll_prev],	rax
+%%skip:
+	mov	qword [%1 + dll_next],	rax
+	mov	qword [rax + dll_next],	rcx
+	mov	qword [rax + dll_value],	%2
+	mov	qword [rax + dll_prev],	%1
+%endm
+
 %endif
diff --git a/main.asm b/main.asm
index 66f73f6..77d214b 100644
--- a/main.asm
+++ b/main.asm
@@ -110,6 +110,49 @@ _main:
 	pop	rax
 	lln_free
 
+	dll_alloc
+	push	rax
+	mov	rbx,	rax
+	mov	r12,	0xDEADBEEF
+	dll_push	rbx,	r12
+	push rax
+	mov	rbx,	[rsp+8]
+	mov	r12,	0xCAFEBABE
+	dll_push	rbx,	r12
+	push	rax
+
+	mov	rbx,	[rsp+16]
+
+	mov	rax,	rbx
+	mov	rax,	[rax + dll_value]
+	REGD	rax
+
+	mov	rax,	rbx
+	dll_seek
+	mov	rax,	[rax + dll_value]
+	REGD	rax
+
+	mov	rax,	rbx
+	dll_seek
+	dll_seek
+	mov	rax,	[rax + dll_value]
+	REGD	rax
+
+	mov	rax,	rbx
+	dll_end
+	mov	rax,	[rax + dll_value]
+	REGD	rax
+
+	pop	rax
+	pop	rax
+	pop	rax
+	dll_end
+.free_loop:
+	mov	rbx,	[rax + dll_prev]
+	dll_free
+	mov	rax,	rbx
+	cmp	rbx,	0
+	jne	.free_loop
 
 	exit_prog
 
-- 
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