Wide Arithmetic Support (128bit uint) #236
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ahangsu
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| class WideUint128DivU64(WideUint128): | ||
| def __init__(self, lhs: WideUint128, arg: Expr): | ||
| WideUint128.__init__(self, 1) |
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@ahangsu Request for clarification: In the following scenarios, I think programs generated via PyTeal do not produce the intended on-chain results. It's quite possible I have gaps in my understanding. Can you double check me?
- Use
WideUint128DivU64for subsequentWideUint128arithmetic (e.g.+).- Concern: The result is 1 uint64. Subsequent arithmetic operations assume a
WideUint128produces 2 outputs (2 uint64).
- Concern: The result is 1 uint64. Subsequent arithmetic operations assume a
- Produce
WideUint128withoutputNum=2, and supply the value as argument to@Subroutine.- Concern: I'm concerned only 1 of 2 stack values will be passed into the subroutine. I didn't fully vet the concern before raising. Trying to gauge if you've considered it before I go deeper.
After addressing the above concerns, taking a step back:
- Is the intent to provide a general purpose wide arithmetic API or to only provide the operations needed to use wide arithmetic operations for intermediate steps?
- It feels to me like the PR attempts to provide a general purpose wide arithmetic API. Though it's unclear to me that the goal is a general purpose API.
This was referenced Sep 23, 2022
Closed
PabloLION
reviewed
Sep 27, 2022
pyteal/ast/widemath.py
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| # stack: [..., A, C, D, B] | ||
| TealOp(expr, Op.uncover, 2), | ||
| # stack: [..., A, C, B, D] | ||
| TealOp(expr, Op.swap), | ||
| # stack: [..., A, C, highword(B + D), lowword(B + D)] | ||
| TealOp(expr, Op.addw), | ||
| # stack: [..., lowword(B + D), A, C, highword(B + D)] | ||
| TealOp(expr, Op.cover, 3), | ||
| # stack: [..., lowword(B + D), highword(B + D), A, C] | ||
| TealOp(expr, Op.cover, 2), | ||
| # stack: [..., lowword(B + D), highword(B + D), A + C] | ||
| TealOp(expr, Op.add), | ||
| # stack: [..., lowword(B + D), highword(B + D) + A + C] | ||
| TealOp(expr, Op.add), | ||
| # stack: [..., highword(B + D) + A + C, lowword(B + D)] | ||
| TealOp(expr, Op.swap), |
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It seems that line 88 and line 94 are not needed here.
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Summary
Provides a set of uint128 (essentially two uint64 values on stack) arithmetic support from 5 wide arithmetic opcodes:
addwmulwdivwdivmodwexpwCloses #101
Testing
Pending, currently only local testing, waiting on e2e semantics test.