Indirect Addressing

aretstudent · Nov 10, 2019

I am trying to understand some indirect addressing. I understand that everything in the brackets must equal a number but how do I interpret this one? What do I do with the comma in this case?

COMP_FR[COMP_N201_0, 58]

ASF · Nov 10, 2019

COMP_FR is a two dimensional array. That is, it's not just an array like so:

Code:

COMP_FR[0]; COMP_FR[1]; COMP_FR[2]; COMP_FR[3]; COMP_FR[4]

...it's an array like so:

Code:

COMP_FR[0,0]; COMP_FR[0,1]; COMP_FR[0,2]; COMP_FR[0,3]; COMP_FR[0,4]
COMP_FR[1,0]; COMP_FR[1,1]; COMP_FR[1,2]; COMP_FR[1,3]; COMP_FR[1,4]
COMP_FR[2,0]; COMP_FR[2,1]; COMP_FR[2,2]; COMP_FR[2,3]; COMP_FR[2,4]
COMP_FR[3,0]; COMP_FR[3,1]; COMP_FR[3,2]; COMP_FR[3,3]; COMP_FR[3,4]
COMP_FR[4,0]; COMP_FR[4,1]; COMP_FR[4,2]; COMP_FR[4,3]; COMP_FR[4,4]

Three dimensional arrays are also possible.

So in your case, one dimension of the array is variable (COMP_N201_0), and the other is fixed (58). If the value of COMP_N201_0 is e.g. 17, your final address is COMP_FR[17, 58]

Don't you just love projects that have been converted from RS500 and had all the data register arrays kept intact?

aretstudent · Nov 10, 2019

Thank You! Now I understand it. You even saw the conversion from RS500! I think this program has been converted several times.

Indirect Addressing

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