Added non-standard Uint24Array, because it's very useful for RGB. Also sped up ArrayBuffer read/write

Author: gfwilliams

ChangeLog

@@ -74,6 +74,7 @@
             Fix stack overflow if executing regex full of hundreds of open brackets (fix #1487)
             Fix issue where STM32F4 USB could lock up if TX during heavy RX
             Improve `E.mapInPlace` docs, and allow it to work with no map (eg pass straight through)
+            Added non-standard Uint24Array, because it's very useful for RGB
 
      1v99 : Increase jslMatch error buffer size to handle "UNFINISHED TEMPLATE LITERAL" string (#1426)
             nRF5x: Make FlashWrite cope with flash writes > 4k

src/jsvar.h

@@ -112,6 +112,7 @@ typedef enum {
   ARRAYBUFFERVIEW_INT8    = 1 | ARRAYBUFFERVIEW_SIGNED,
   ARRAYBUFFERVIEW_UINT16  = 2,
   ARRAYBUFFERVIEW_INT16   = 2 | ARRAYBUFFERVIEW_SIGNED,
+  ARRAYBUFFERVIEW_UINT24  = 3,
   ARRAYBUFFERVIEW_UINT32  = 4,
   ARRAYBUFFERVIEW_INT32   = 4 | ARRAYBUFFERVIEW_SIGNED,
   ARRAYBUFFERVIEW_FLOAT32 = 4 | ARRAYBUFFERVIEW_FLOAT,

src/jsvariterator.c

@@ -345,13 +345,12 @@ static void jsvArrayBufferIteratorGetValueData(JsvArrayBufferIterator *it, char
 
 static JsVarInt jsvArrayBufferIteratorDataToInt(JsvArrayBufferIterator *it, char *data) {
   unsigned int dataLen = JSV_ARRAYBUFFER_GET_SIZE(it->type);
-  JsVarInt v = 0;
-  if (dataLen==1) v = *(int8_t*)data;
-  else if (dataLen==2) v = *(short*)data;
-  else if (dataLen==4) return *(int*)data;
-  else assert(0);
-  if ((!JSV_ARRAYBUFFER_IS_SIGNED(it->type)))
-    v = v & (JsVarInt)((1UL << (8*dataLen))-1);
+  unsigned int bits = 8*dataLen;
+  JsVarInt mask = (JsVarInt)((1UL << bits)-1);
+  JsVarInt v = *(int*)data;
+  v = v & mask;
+  if (JSV_ARRAYBUFFER_IS_SIGNED(it->type) && (v&(JsVarInt)(1UL<<(bits-1))))
+    v |= ~mask;
   return v;
 }
 
@@ -415,12 +414,9 @@ static void jsvArrayBufferIteratorIntToData(char *data, unsigned int dataLen, in
     if (v<0) v=0;
     if (v>255) v=255;
   }
-  // we don't care about sign when writing - as it gets truncated
-  if (dataLen==1) { data[0] = (char)v; }
-  else if (dataLen==2) { *(short*)data = (short)v; }
-  else if (dataLen==4) { *(int*)data = (int)v; }
-  else if (dataLen==8) { *(long long*)data = (long long)v; }
-  else assert(0);
+  // we don't care about sign when writing (or any extra bytes!) - as it gets truncated
+  if (dataLen==8) *(long long*)data = (long long)v;
+  else *(int*)data = (int)v;
 }
 
 static void jsvArrayBufferIteratorFloatToData(char *data,  unsigned int dataLen, int type, JsVarFloat v) {

src/jswrap_arraybuffer.c

@@ -40,6 +40,7 @@ This is the built-in JavaScript class that is the prototype for:
 * [Int8Array](/Reference#Int8Array)
 * [Uint16Array](/Reference#Uint16Array)
 * [Int16Array](/Reference#Int16Array)
+* [Uint24Array](/Reference#Uint24Array) (Espruino-specific - not standard JS)
 * [Uint32Array](/Reference#Uint32Array)
 * [Int32Array](/Reference#Int32Array)
 * [Float32Array](/Reference#Float32Array)
@@ -112,6 +113,20 @@ This is the built-in JavaScript class for a typed array of 16 bit signed integer
 
 Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).
 
+Arrays of this type include all the methods from [ArrayBufferView](/Reference#ArrayBufferView)
+ */
+/*JSON{
+  "type" : "class",
+  "class" : "Uint24Array",
+  "ifndef" : "SAVE_ON_FLASH",
+  "prototype" : "ArrayBufferView",
+  "check" : "jsvIsArrayBuffer(var) && var->varData.arraybuffer.type==ARRAYBUFFERVIEW_UINT24",
+  "not_real_object" : "Don't treat this as a real object - it's handled differently internally"
+}
+This is the built-in JavaScript class for a typed array of 24 bit unsigned integers.
+
+Instantiate this in order to efficiently store arrays of data (Espruino's normal arrays store data in a map, which is inefficient for non-sparse arrays).
+
 Arrays of this type include all the methods from [ArrayBufferView](/Reference#ArrayBufferView)
  */
 /*JSON{
@@ -298,12 +313,28 @@ Create a typed array based on the given input. Either an existing Array Buffer,
   "return" : ["JsVar","A typed array"],
   "return_object" : "ArrayBufferView"
 }
+Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBuffer view (eg. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.
+ */
+/*JSON{
+  "type" : "constructor",
+  "class" : "Uint24Array",
+  "name" : "Uint24Array",
+  "generate_full" : "jswrap_typedarray_constructor(ARRAYBUFFERVIEW_UINT24, arr, byteOffset, length)",
+  "params" : [
+    ["arr","JsVar","The array or typed array to base this off, or an integer which is the array length"],
+    ["byteOffset","int","The byte offset in the ArrayBuffer  (ONLY IF the first argument was an ArrayBuffer)"],
+    ["length","int","The length (ONLY IF the first argument was an ArrayBuffer)"]
+  ],
+  "return" : ["JsVar","A typed array"],
+  "return_object" : "ArrayBufferView"
+}
 Create a typed array based on the given input. Either an existing Array Buffer, an Integer as a Length, or a simple array. If an ArrayBuffer view (eg. Uint8Array rather than ArrayBuffer) is given, it will be completely copied rather than referenced.
  */
 /*JSON{
   "type" : "constructor",
   "class" : "Uint32Array",
   "name" : "Uint32Array",
+  "ifndef" : "SAVE_ON_FLASH",
   "generate_full" : "jswrap_typedarray_constructor(ARRAYBUFFERVIEW_UINT32, arr, byteOffset, length)",
   "params" : [
     ["arr","JsVar","The array or typed array to base this off, or an integer which is the array length"],