mtdbg: Added binary search near symbol

Signed-off-by: Max Logaev <maxlogaev@proton.me>

programs/develop/mtdbg/symbols.inc

@@ -467,28 +467,65 @@ find_symbol_name:
         ret
 
 ;-----------------------------------------------------------------------------
+;   
+; Find the nearest symol using binary search
 ;
-; in:  eax - addres
+; in:  eax - target addres
 ; out: esi - symbol name
-; destroys: ebx, edx
+; destroys: ebx, ecx, edx, edi, ebp
 ;
 find_near_symbol:
-        mov     ebx, [symbols] 
-        mov     ecx, [num_symbols]
-        xor     esi, esi
+        mov     edi, [symbols] 
+        
+        xor     esi, esi            ; Result
+        mov     ecx, esi            ; Left
+        mov     edx, [num_symbols]  ; Right
+        dec     edx
+        js      .end       
 
-    .next:
-        dec     ecx
-        js      .end
+        ; If the first address is already greater than the target
+        mov     ebp, [edi + ecx * sizeof.DEBUG_SYMBOL]
+        cmp     [ebp + DEBUG_SYMBOL.addr], eax
+        ja      .end
 
-        ; The symbols have already been sorted:
-        ; from smallest address to the largest. 
-        ; Therefore, checking addresses from the end.
-        mov     edx, [ebx + ecx * sizeof.DEBUG_SYMBOL]
-        cmp     eax, [edx + DEBUG_SYMBOL.addr]
-        jb      .next
+        ; If the last address is less than or equal to the target
+        mov     ebp, [edi + edx * sizeof.DEBUG_SYMBOL]
+        cmp     [ebp + DEBUG_SYMBOL.addr], eax
+        jbe     .found
 
-        mov     esi, edx
+    .loop:
+        cmp     ecx, edx
+        ja      .end
+
+        ; Calc middle:
+        mov     ebx, edx            ; Middle
+        sub     ebx, ecx            ; (right - left)
+        shr     ebx, 1              ;  / 2
+        add     ebx, ecx            ; + left
+
+        ; Equal
+        mov     ebp, [edi + ebx * sizeof.DEBUG_SYMBOL]
+        cmp     [ebp + DEBUG_SYMBOL.addr], eax
+        jz      .found
+        jb      .update_left
+
+        ; Update right
+        mov     edx, ebx
+        dec     edx
+        jmp     .loop
+
+    .update_left:
+        ; Save potential result
+        mov     esi, ebp
+        add     esi, DEBUG_SYMBOL.string
+
+        ; Update left
+        mov     ecx, ebx
+        inc     ecx
+        jmp     .loop
+
+    .found:
+        mov     esi, ebp
         add     esi, DEBUG_SYMBOL.string
 
     .end: