Re:The Earliest Unix Code: An Anniversary Source Code Release
by boomlinde on Friday October 18, 2019 @05:21AM
(#21289839)
It looks like there are symbols named "sin" and "cos" not declared in the program. These are possibly system provided tables.
Accesses to "sin" and "cos" are preceded by what looks like a self modifying store ("dac .+3", interpreted to mean "deposit accumulator at current program counter + 3"), possibly to modify the "lac sin" and "lac cos" instructions to index the tables, but I'm not familiar with the instruction encoding.
If so, this is a relatively straight forward, non-magic way of implementing trigonometric functions.
Accesses to "sin" and "cos" are preceded by what looks like a self modifying store ("dac .+3", interpreted to mean "deposit accumulator at current program counter + 3"), possibly to modify the "lac sin" and "lac cos" instructions to index the tables, but I'm not familiar with the instruction encoding.
If so, this is a relatively straight forward, non-magic way of implementing trigonometric functions.