It took me longer to format this to paste it in here than it did to generate it.
Convert the following code into Xojo
int32_t intVal=0x12345678;
uint16_t lowWord=(intVal & 0xFFFF);
uint16_t highWord=((intVal>>16)) & 0xFFFF);
Dim intVal As Int32 = &h12345678
Dim lowWord As UInt16 = intVal And &hFFFF
Dim highWord As UInt16 = (intVal >> 16) And &hFFFF
Xojo doesn’t use >> for shifting
You’re correct! Xojo uses the Bitwise.ShiftRight operator to perform a bitwise right shift. Here’s the updated code:
Dim intVal As Int32 = &h12345678
Dim lowWord As UInt16 = intVal And &hFFFF
Dim highWord As UInt16 = Bitwise.ShiftRight(intVal, 16) And &hFFFF
This should give you the same result as the original C++ code.
Please explain the code
Certainly! Let me break down the code line by line:
Dim intVal As Int32 = &h12345678
This line declares a variable intVal of type Int32 (a 32-bit integer), and assigns it the hexadecimal value &h12345678.
Dim lowWord As UInt16 = intVal And &hFFFF
This line declares a variable lowWord of type UInt16 (a 16-bit unsigned integer), and assigns it the result of a bitwise AND operation between intVal and the hexadecimal value &hFFFF (which is equivalent to binary 1111111111111111). This operation effectively extracts the lower 16 bits (the “low word”) of intVal.
Dim highWord As UInt16 = Bitwise.ShiftRight(intVal, 16) And &hFFFF
This line declares a variable highWord of type UInt16, and assigns it the result of two operations. The first operation is a bitwise right shift of intVal by 16 bits, which effectively moves the upper 16 bits (the “high word”) of intVal into the lower 16 bits. The second operation is a bitwise AND with &hFFFF, which effectively clears the upper 16 bits and leaves only the lower 16 bits. This gives us the upper 16 bits (the “high word”) of the original intVal.
So, overall, these three lines of code extract the lower 16 bits and upper 16 bits of a 32-bit integer value, using bitwise operations to mask and shift the bits as needed.
Reverse the process to end up with an Int32
Sure thing! Here’s how you can reverse the process to combine the lowWord and highWord variables into an Int32:
Dim lowWord As UInt16 = &h5678
Dim highWord As UInt16 = &h1234
Dim intVal As Int32 = Bitwise.ShiftLeft(highWord, 16) Or lowWord
This code assumes you have already extracted the lower 16 bits (lowWord) and upper 16 bits (highWord) of an Int32 value, and assigns them to variables of type UInt16.
The first line declares a variable lowWord and assigns it the value &h5678 (which is the hexadecimal representation of the lower 16 bits).
The second line declares a variable highWord and assigns it the value &h1234 (which is the hexadecimal representation of the upper 16 bits).
The third line uses bitwise operations to combine lowWord and highWord into a single Int32. The Bitwise.ShiftLeft operator shifts the bits in highWord 16 positions to the left, effectively moving them to the upper 16 bits of the resulting Int32. The Or operator then combines the shifted highWord with lowWord, effectively combining the upper and lower 16 bits into a single 32-bit value.
So, overall, these three lines of code reverse the process of extracting the lower and upper 16 bits from an Int32, and combine them back into a single Int32 value.
I like