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C/C++ COMPILER->Scratch Registers

The scratch registers differ depending upon whether or not the Advanced Features of the compiler are enabled.

If Advanced Features are not enabled:

Scratch registers are data registers D0, D1, D2 and address registers A0 and A1.

Floating point scratch registers are pseudo registers __CW68D002, __CW68D003 and __CW68D004  or, if the chip has a floating point unit, in floating point register FP0, FP1 and FP2.

The values of the scratch registers will be saved, if necessary, before a function is called.

If Advanced Features are enabled:

Scratch registers are data registers D0, D1 and address registers A0 and A1.  If the chip has a floating point unit, floating point register FP0 and FP1 are also scratch registers.

The compiler will ensure that scratch registers are not in use when a function is called (unless they are being used to pass parameters to the function).