...so apparently the VC4 doesn't have ADC or SBC instructions (add and
subtract with carry).
I can probably the input part of ADC with:
addcs r0, #1 ; adds on incoming C
add r0, r1 ; does the rest of the add
And I can probably fake the output part of ADC with:
cmn r0, r1 ; sets C
add r0, r1 ; actually does the add
But (a) this is horrible, and (b) combining the two such that I honour
incoming carry *and* correctly set outgoing carry is rather nontrivial.
Has anyone seen any examples of 64-bit arithmetic in compiled code?
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