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fix

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This commit is contained in:
Nicholas Ward 2022-09-30 12:07:25 -07:00
parent 416a7a868b
commit 249fc6c1e4
1 changed files with 0 additions and 76 deletions
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76
evm/src/cpu/kernel/asm/modexp.asm
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@ -1,76 +0,0 @@
/// Recursive implementation of exp.
/// Equivalent to:
/// def exp(x, e):
/// if e == 0:
/// # The path where JUMPI does not jump to `step_case`
/// return 1
/// else:
/// # This is under the `step_case` label
/// return (x if e % 2 else 1) * exp(x * x, e // 2)
/// Note that this correctly handles exp(0, 0) == 1.
global modexp:
// stack: x, e, retdest
dup2
// stack: e, x, e, retdest
%jumpi(step_case)
// stack: x, e, retdest
pop
// stack: e, retdest
pop
// stack: retdest
push 1
// stack: 1, retdest
swap1
// stack: retdest, 1
jump
step_case:
// stack: x, e, retdest
push recursion_return
// stack: recursion_return, x, e, retdest
push 2
// stack: 2, recursion_return, x, e, retdest
dup4
// stack: e, 2, recursion_return, x, e, retdest
div
// stack: e / 2, recursion_return, x, e, retdest
dup3
// stack: x, e / 2, recursion_return, x, e, retdest
%square
// stack: x * x, e / 2, recursion_return, x, e, retdest
%jump(exp)
recursion_return:
// stack: exp(x * x, e / 2), x, e, retdest
push 2
// stack: 2, exp(x * x, e / 2), x, e, retdest
dup4
// stack: e, 2, exp(x * x, e / 2), x, e, retdest
mod
// stack: e % 2, exp(x * x, e / 2), x, e, retdest
push 1
// stack: 1, e % 2, exp(x * x, e / 2), x, e, retdest
dup4
// stack: x, 1, e % 2, exp(x * x, e / 2), x, e, retdest
sub
// stack: x - 1, e % 2, exp(x * x, e / 2), x, e, retdest
mul
// stack: (x - 1) * (e % 2), exp(x * x, e / 2), x, e, retdest
push 1
// stack: 1, (x - 1) * (e % 2), exp(x * x, e / 2), x, e, retdest
add
// stack: 1 + (x - 1) * (e % 2), exp(x * x, e / 2), x, e, retdest
mul
// stack: (1 + (x - 1) * (e % 2)) * exp(x * x, e / 2), x, e, retdest
swap3
// stack: retdest, x, e, (1 + (x - 1) * (e % 2)) * exp(x * x, e / 2)
swap2
// stack: e, x, retdest, (1 + (x - 1) * (e % 2)) * exp(x * x, e / 2)
pop
// stack: x, retdest, (1 + (x - 1) * (e % 2)) * exp(x * x, e / 2)
pop
// stack: retdest, (1 + (x - 1) * (e % 2)) * exp(x * x, e / 2)
jump
global sys_exp:
PANIC