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--- re-dimensioning_20arrays [2018/04/17 18:21]
tbest3112 Added syntax highlighting
+++ re-dimensioning_20arrays [2019/04/09 22:08] (current)
richardrussell Added BBCSDL procedures
@@ Line 1: / Line 1: @@
 =====Re-dimensioning arrays=====
-//by Richard Russell, May 2014//\\ \\  BBC BASIC does not have a **REDIM** or **REDIM PRESERVE** statement, as found in some other dialects of BASIC (REDIM allows you to increase the dimensions of an existing array - the contents are lost - and REDIM PRESERVE allows you to increase the dimensions of an array without destroying its contents). However it is not difficult to provide an equivalent functionality using user-defined procedures:\\
+//by Richard Russell, May 2014//\\ \\  BBC BASIC does not have a **REDIM** or **REDIM PRESERVE** statement, as found in some other dialects of BASIC (REDIM allows you to increase the dimensions of an existing array - the contents are lost - and REDIM PRESERVE allows you to increase the dimensions of an array without destroying its contents). However it is not difficult to provide an equivalent functionality using user-defined procedures (these are for BB4W, for BBCSDL see below):\\
 <code bb4w>
         DEF PROCredim1d(RETURN P%,S%,D%)
@@ Line 72: / Line 72: @@
         PROCredim1d(array$(), ^array$(1)-^array$(0), newsize%)
 </code>
-\\  The most reliable way of determining the element size is to calculate it at run-time, as in the above examples, but for reference here are the appropriate sizes for each type of array:\\ \\
+Here are equivalent procedures for //BBC BASIC for SDL 2.0//:
+<code bb4w>
+      DEF PROCredim1d(RETURN p%%,S%,D%)
+      LOCAL a%%,N%
+      IF ?p%%<>1 ERROR 14, "Bad use of array"
+      N% = 5+S%*(D%+1)
+      IF p%%<LOMEM OR p%%>HIMEM SYS "free", p%%
+      SYS "malloc", N% TO a%%
+      IF @platform% AND &40 ELSE a%%=!^a%%
+      IF a%%=0 ERROR 11, "DIM space"
+      SYS "memset", a%%, 0, N%
+      ?a%%=1 : a%%!1=D%+1
+      p%% = a%%
+      ENDPROC
+      DEF PROCredim2d(RETURN p%%,S%,D%,E%)
+      LOCAL a%%,N%
+      IF ?p%%<>2 ERROR 14, "Bad use of array"
+      N% = 9+S%*(D%+1)*(E%+1)
+      IF p%%<LOMEM OR p%%>HIMEM SYS "free", p%%
+      SYS "malloc", N% TO a%%
+      IF @platform% AND &40 ELSE a%%=!^a%%
+      IF a%%=0 ERROR 11, "DIM space"
+      SYS "memset", a%%, 0, N%
+      ?a%%=2 : a%%!1=D%+1 : a%%!5=E%+1
+      p%% = a%%
+      ENDPROC
+      DEF PROCredimpreserve1d(RETURN p%%,S%,D%)
+      LOCAL a%%,N%,O%
+      IF ?p%%<>1 ERROR 14, "Bad use of array"
+      N% = 5+S%*(D%+1)
+      O% = 5+S%*p%%!1
+      SYS "malloc", N% TO a%%
+      IF @platform% AND &40 ELSE a%%=!^a%%
+      IF a%%=0 ERROR 11, "DIM space"
+      IF N%>O% SWAP N%,O%
+      SYS "memmove", a%%, p%%, N%
+      a%%!1=D%+1
+      IF p%%<LOMEM OR p%%>HIMEM SYS "free", p%%
+      p%% = a%%
+      ENDPROC
+      DEF PROCredimpreserve2d(RETURN p%%,S%,D%,E%)
+      LOCAL a%%,N%,O%
+      IF ?p%%<>2 ERROR 14, "Bad use of array"
+      N% = 9+S%*(D%+1)*(E%+1)
+      O% = 9+S%*p%%!1*p%%!5
+      SYS "malloc", N% TO a%%
+      IF @platform% AND &40 ELSE a%%=!^a%%
+      IF a%%=0 ERROR 11, "DIM space"
+      IF N%>O% SWAP N%,O%
+      SYS "memmove", a%%, p%%, N%
+      a%%!1=D%+1 : a%%!5=E%+1
+      IF p%%<LOMEM OR p%%>HIMEM SYS "free", p%%
+      p%% = a%%
+      ENDPROC
+</code>
+The most reliable way of determining the element size is to calculate it at run-time, as in the above examples, but for reference here are the appropriate sizes for each type of array:\\
 | **byte** e.g. array&()\\ | size=**1**\\ |
@@ Line 82: / Line 143: @@
 | **64-bit integer** e.g. array%%() \\ | size=**8***\\ |
 | **80-bit float** e.g. array()\\ | size=**10***\\ |
- * BB4W version 6 only
+ * BB4W version 6 or BBCSDL

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