X-Git-Url: https://git.danieliu.xyz/?p=sped.git;a=blobdiff_plain;f=utils.asm;h=9feb498d6e76de0e045391980ac18792025b34ad;hp=fd8529dd6dc17d88a4460fd6768a2c7963baa8a1;hb=6cf67300c03d92a9cc0c5888b33cdb21a852eb69;hpb=89732d399de9007aaf2894b0c637e8cfb9ed47ac

diff --git a/utils.asm b/utils.asm
index fd8529d..9feb498 100644
--- a/utils.asm
+++ b/utils.asm
@@ -1,21 +1,72 @@
 
+%include "macros.S"
+
 extern memmove
+extern free
+extern realloc
 
 global shiftLeft
 global shiftRight
 
 section .text
 
+; shrinks array (4byte) by shifting blocks left
+; args: buffer, buffer_len, shift_pos (index that gets destroyed)
+; return:
+;   eax: location of new buffer
+; issues: 
 shiftLeft:
+    %define _BUFFER      16
+    %define _BUFFER_LEN  12
+    %define _SHIFT_POS   8
+    %define SHIFT_LEN    4
+    %define BLOCK_OFFSET 8 ; mem location of block to be destroyed
+    %define NEW_BUFFER   12
+
     push ebp
     mov ebp, esp
+
+    sub esp, 12
+
+    ; set vars
+    mov eax, DWORD [ebp+_BUFFER_LEN]
+    sub eax, [ebp+_SHIFT_POS]
+    sub eax, 1
+    mov [ebp-SHIFT_LEN], eax
+
+    str_offset [ebp+_BUFFER], [ebp+_SHIFT_POS]
+    mov [ebp-BLOCK_OFFSET], eax
     
+    ; free string to be destoryed first
+    mov eax, DWORD [ebp-BLOCK_OFFSET]
+    mov eax, [eax]
+    push eax
+    call free
+
+    ; move the memory
+    mov eax, DWORD [ebp-SHIFT_LEN]
+    mov ecx, 4
+    mul ecx
+    push eax
+    mov eax, DWORD [ebp-BLOCK_OFFSET]
+    add eax, 4
+    push eax
+    push DWORD [ebp-BLOCK_OFFSET]
+    call memmove
     
+    ; realloc to shrink the array
+
+    %undef _BUFFER
+    %undef _BUFFER_LEN
+    %undef _SHIFT_POS
     
     mov esp, ebp
     pop ebp
     ret
 
+; grows array by shifting blocks right
+; args: buffer, buffer_len, shift_pos (new uninitalized index)
+; return: location of new buffer
 shiftRight:
     push ebp
     mov ebp, esp
@@ -25,3 +76,4 @@ shiftRight:
     mov esp, ebp
     pop ebp
     ret
+