add the function list_insert.HEADmaster

the function inserts a new element at the position specified in its
third argument.

example:

list_clear(&list);
list_insert(&list, 2, 0);
list_insert(&list, 1, 0);
list_insert(&list, 3, 2);
list_insert(&list, 0, 0);

the list will contain [0, 1, 2, 3]

2 files changed, 76 insertions, 8 deletions

diff --git a/list.asm b/list.asm
index 8932eaf..20e6688 100644
--- a/list.asm
+++ b/list.asm
@@ -95,22 +95,28 @@ list_clear: ;; {{{
     ret
 
 ;; }}}
-list_append: ;; {{{
-
-    enter 0x18, 0
-
-    mov [rsp], rdi
-    mov [rsp + 8], rsi
 
+%macro rethrow_create_element 0
     mov rdi, elem_t_size
     call malloc
 
     test rax, rax
-    jne .malloc_succeed
+    jne %%malloc_succeed
     mov rax, -1
     jmp .end
 
-    .malloc_succeed:
+    %%malloc_succeed
+%endmacro
+
+list_append: ;; {{{
+
+    enter 0x18, 0
+
+    mov [rsp], rdi
+    mov [rsp + 8], rsi
+
+    rethrow_create_element
+
     ; set the new element
     mov rsi, QWORD [rsp + 8]
     mov QWORD [rax + elem_t.next], 0
@@ -141,6 +147,64 @@ list_append: ;; {{{
     ret
 
 ;; }}}
+list_insert: ;; {{{
+
+    enter 0, 0
+
+    cmp edx, DWORD [rdi + list_t.size]
+    jg .error
+
+    inc DWORD [rdi + list_t.size]
+
+    push rdx
+    push rsi
+    push rdi
+    rethrow_create_element
+    pop rdi
+    pop rsi
+    pop rcx
+
+    ; set the element
+    mov QWORD [rax + elem_t.value], rsi
+
+    test ecx, ecx
+    jnz .insert
+
+    ; this will be the first element
+    mov r8, QWORD [rdi + list_t.first]
+    mov QWORD [rax + elem_t.next], r8
+    mov QWORD [rdi + list_t.first], rax
+
+    jmp .success
+
+    ; this is not the first element
+    .insert:
+    mov rdi, QWORD [rdi + list_t.first]
+
+    .loop:
+    dec ecx
+    test ecx, ecx
+    jz .loop_ended
+    mov rdi, QWORD [rdi + elem_t.next]
+    jmp .loop
+
+    .loop_ended:
+    mov r8, QWORD [rdi + elem_t.next]
+    mov QWORD [rax + elem_t.next], r8
+    mov QWORD [rdi + elem_t.next], rax
+
+    .success:
+    xor rax, rax
+    jmp .end
+
+    .error:
+    mov rax, -1
+
+    .end:
+    leave
+    ret
+
+;; }}}
 list_apply: ;; {{{
 
     enter 0x14, 0
diff --git a/public.asm b/public.asm
index 0a90fe8..f4c216f 100644
--- a/public.asm
+++ b/public.asm
@@ -40,6 +40,10 @@ global list_clear:function
 ;; otherwise (on success), $rax will be set to 0
 global list_append:function
 
+;; like list_append but instead of adding at the end of the list, this
+;; function adds at the position $rdx
+global list_insert:function
+
 ;; for every element in the list stored at address $rdi, call the function
 ;; pointed to by $rsi with the value of the current element.
 global list_apply:function