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--- allocating_20arrays_20using_20the_20windows_20api [2018/04/17 15:01] – Added syntax highlighting tbest3112
+++ allocating_20arrays_20using_20the_20windows_20api [2024/01/05 00:22] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-=====Allocating arrays using the Windows API=====
+=====Allocating arrays using the Windows or SDL 2.0 API=====
 //by Richard Russell, December 2006//\\ \\  You can allocate arrays, using **DIM**, either on BASIC's //heap// (global and PRIVATE arrays) or on the //stack// (LOCAL arrays). Using a combination of these will satisfy the needs of most programs. For example a skeleton program might be structured as follows:\\ \\
@@ Line 28: / Line 28: @@
   - Destroy first array
   - Destroy second array
-\\  Because LOCAL arrays are allocated on the //stack// they can only be destroyed in the reverse order from which they were created.\\ \\  In these cases it is possible to utilise the capabilities of the **Windows API** to allocate and free the memory used by arrays. By setting BASIC's internal pointers to the allocated memory such arrays can be used exactly as if they were declared using **DIM**, but the restrictions on size and sequence of creation and destruction are removed.\\ \\  The routines listed below illustrate how this can be achieved. For simplicity a separate routine is listed for 1-dimensional and 2-dimensional arrays. It should be relatively easy to see how this can be extended to arrays with more dimensions:\\ \\
+\\  Because LOCAL arrays are allocated on the //stack// they can only be destroyed in the reverse order from which they were created.\\ \\  In these cases it is possible to utilise the capabilities of the **Windows or SDL 2.0 API** to allocate and free the memory used by arrays. By setting BASIC's internal pointers to the allocated memory such arrays can be used exactly as if they were declared using **DIM**, but the restrictions on size and sequence of creation and destruction are removed.\\ \\  The routines listed below illustrate how this can be achieved. For simplicity a separate routine is listed for 1-dimensional and 2-dimensional arrays. It should be relatively easy to see how this can be extended to arrays with more dimensions:
+**BBC BASIC for Windows:**
 <code bb4w>
         DEF PROCdim1d(RETURN A(),S%,D1%)
@@ Line 49: / Line 51: @@
         ENDPROC
 </code>
+**BBC BASIC for SDL 2.0:**
+<code bb4w>
+      DEF PROCdim1d(RETURN A(),S%,D1%)
+      LOCAL a%%
+      SYS "SDL_malloc", 5+S%*(D1%+1) TO a%%
+      IF @platform% AND &40 ELSE a%% = !^a%%
+      ?a%%=1 : a%%!1=D1%+1
+      PTR(A()) = a%%
+      ENDPROC
+      DEF PROCdim2d(RETURN A(),S%,D1%,D2%)
+      LOCAL a%%
+      SYS "SDL_malloc", 9+S%*(D1%+1)*(D2%+1) TO a%%
+      IF @platform% AND &40 ELSE a%% = !^a%%
+      ?a%%=2 : a%%!1=D1%+1 : a%%!5=D2%+1
+      PTR(A()) = a%%
+      ENDPROC
+      DEF PROCundim(RETURN A())
+      SYS "SDL_free", PTR(A())
+      PTR(A()) = 0
+      ENDPROC
+</code>
 In each case the parameters supplied to the **PROCdim** procedure are the name of the array to be created, the size (in bytes) of each array element and the array's dimension(s). The element size should be specified as follows:\\ \\