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Remove ROR/ROL

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Alex Beregszaszi 2017-04-23 11:28:25 +01:00
parent 4bab8793ed
commit a63aef39d1
1 changed files with 1 additions and 23 deletions
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EIPS/eip-draft_bitwise_shifts.md
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@ -59,29 +59,7 @@ Notes:
- `arg1` is interpreted as unsigned number.
- If the shift amount is greater or equal 256 the result is 0 if `arg2` is non-negative or -1 if `arg2` is negative.
### `0x1e`: `ROL` (rotate left)
The `ROL` instruction (rotate left) pops 2 values from the stack, `arg1` and `arg2`, and pushes on the stack the second popped value `arg2` circular shifted to the left by the number of bits in the first popped value `arg1`.
```
(arg1 shl arg2) or (arg1 shr (256 - arg2)
```
Notes:
- `arg2 rol arg1` is equivalent of `arg2 rol (arg1 mod 2^256)`
### `0x1f`: `ROR` (rotate right)
The `ROL` instruction (rotate right) pops 2 values from the stack, `arg1` and `arg2`, and pushes on the stack the second popped value `arg2` circular shifted to the right by the number of bits in the first popped value `arg1`.
```
(arg1 shr arg2) or (arg1 shl (256 - arg2)
```
Notes:
- `arg2 ror arg1` is equivalent of `arg2 ror (arg1 mod 2^256)`
The cost of the shift instructions is set at `verylow` tier (3 gas), while the rotations are 12 gas each.
The cost of the shift instructions is set at `verylow` tier (3 gas).
## Rationale