EnsureLargeEnoughWave: Avoid resizing when not needed

We don't need to look at the minimum wave size when the requested index
already fits.

We now also ensure that we double the wave sizes so that we should end up
always with a power of two when we started with one.

Author: t-b

Packages/MIES/MIES_Utilities_WaveHandling.ipf

@@ -45,6 +45,8 @@ threadsafe Function EnsureLargeEnoughWave(WAVE wv, [variable indexShouldExist, v
 
 	if(ParamIsDefault(dimension))
 		dimension = ROWS
+	else
+		ASSERT_TS(dimension == ROWS || dimension == COLS || dimension == LAYERS || dimension == CHUNKS, "Invalid dimension")
 	endif
 
 	if(ParamIsDefault(checkFreeMemory))
@@ -53,21 +55,18 @@ threadsafe Function EnsureLargeEnoughWave(WAVE wv, [variable indexShouldExist, v
 		checkFreeMemory = !!checkFreeMemory
 	endif
 
-	ASSERT_TS(dimension == ROWS || dimension == COLS || dimension == LAYERS || dimension == CHUNKS, "Invalid dimension")
 	ASSERT_TS(WaveExists(wv), "Wave does not exist")
 	ASSERT_TS(IsFinite(indexShouldExist) && indexShouldExist >= 0, "Invalid minimum size")
 
 	if(ParamIsDefault(indexShouldExist))
 		indexShouldExist = MINIMUM_WAVE_SIZE - 1
-	else
-		indexShouldExist = max(MINIMUM_WAVE_SIZE - 1, indexShouldExist)
 	endif
 
 	if(indexShouldExist < DimSize(wv, dimension))
 		return 0
 	endif
 
-	indexShouldExist *= 2
+	indexShouldExist = max(max(2^FindNextPower(indexShouldExist, 2), 2 * DimSize(wv, dimension)), MINIMUM_WAVE_SIZE)
 
 	if(checkFreeMemory)
 		if((GetWaveSize(wv) * (indexShouldExist / DimSize(wv, dimension)) / 1024 / 1024 / 1024) >= GetFreeMemory())

Packages/tests/Basic/UTF_Utils_WaveHandling.ipf

@@ -160,6 +160,33 @@ Function ELE_AbortsWithTooLargeValue()
 	endtry
 End
 
+Function ELE_DoesNothingIfIndexIsGood()
+
+	Make/FREE/N=(1) wv
+	EnsurelargeEnoughWave(wv, indexShouldExist = 0)
+	CHECK_EQUAL_VAR(DimSize(wv, ROWS), 1)
+End
+
+Function ELE_ResizesGeometrically()
+
+	Make/FREE/N=(MINIMUM_WAVE_SIZE) wv
+	EnsurelargeEnoughWave(wv, indexShouldExist = MINIMUM_WAVE_SIZE + 1)
+	CHECK_EQUAL_VAR(DimSize(wv, ROWS), 2 * MINIMUM_WAVE_SIZE)
+
+	EnsurelargeEnoughWave(wv, indexShouldExist = 2 * MINIMUM_WAVE_SIZE + 1)
+	CHECK_EQUAL_VAR(DimSize(wv, ROWS), 4 * MINIMUM_WAVE_SIZE)
+
+	EnsurelargeEnoughWave(wv, indexShouldExist = 9 * MINIMUM_WAVE_SIZE)
+	CHECK_EQUAL_VAR(DimSize(wv, ROWS), 16 * MINIMUM_WAVE_SIZE)
+End
+
+Function ELE_WorksWithEmtpyInitialSize()
+
+	Make/FREE/N=(0) wv
+	EnsurelargeEnoughWave(wv, indexShouldExist = 0)
+	CHECK_EQUAL_VAR(DimSize(wv, ROWS), MINIMUM_WAVE_SIZE)
+End
+
 /// @}
 
 // GetWaveSize