Posts tagged c

Optimizing C array lookups for the 6502

Most of the platforms in the IDE that are powerful enough to support a C compiler are Z80-based. The Z80 isn’t the easiest target for C, but at least it has a lot of registers.

While the 6502 only has three 8-bit registers, the 6502 has strengths the Z80 doesn’t, as we’ll see here.

Let’s compare the two dominant C compilers for these CPUs. We’ll compile a function with the CC65 C compiler for the 6502, and then with the SDCC (Small Device C Compiler) for the Z80. We’ll call the function getValue():

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