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Correct formula for division.

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Greg Colvin 2017-05-05 20:52:53 -04:00 committed by GitHub
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EIPS/eip-EIPS/eip-616.md
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@ -1,5 +1,5 @@
```
EIP: <to be assigned>
EIP: 616
Title: SIMD Operations for the EVM
Author: Greg Colvin, greg@colvin.org
Type: Standard Track
@ -125,7 +125,7 @@ operation | cycles | N = 2 | N = 4 | N = 8
add | 10 _N_ + 6 | 26 | 46 | 86
subtract | 12 _N_ + 3 |27 | 51 | 99
multiply | 28 _N_**2 + 11 _N_ + 3 | 137 | 495 |1883
divide | 30 _N_**2 + 119 _N_ + 111 | 469 | 1067 | 2983
divide | 30 (_N_**2)/2 + 119 _N_ + 111 | 409 | 827 | 2023
The remaining operations are of about the same complexity as addition and subtraction, or less. Given that JUMPDEST is a no-op, and is assigned a gas price of 1, this can be taken as the overhead of the interpreter. All of the arithmetic operations are assigned the same gas price of 5, for a remaining runtime of 4. The interpreter loop itself takes about 6 to 8 C instructions, so ADD and SUB are reasonably priced, but MUL is some 5 to 21 times slower than ADD or SUB, and DIV is some 18 to 35 times slower, so they are clearly mispriced.