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B1C2 Load IWA with 1-byte Integer value

Submitted by Steve Fewell

Routine:loadbyte
Name: Load IWA with 1-byte Integer value
Starting Address: &B1C2
Entry criteria: &2A and &2B point to the address of the variable's value.
Y is 0.
Exit: The IWA contains the value of the variable.
The address in (&2A and &2B) is destroyed.

Description:

Load the 1-byte Integer from the address pointed to by (&2A, &2B) and exit
via the IWA = 8-bit Integer routine which sets the Least significant byte of the IWA
to the 1-byte value [A] (&2A), &2B to the value of Y (which is zero), &2C to
zero and &2D (IWA most significant byte) to zero.


Disassembly for the Load IWA with 1-byte Integer value routine

B1C2 * 177 042 B1 2A LDA (&2A),Y
B1C4 L 076 026 174 4C 1A AE JMP &AE1A Load IWA with 2-byte value (A and Y)

 


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