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core/vm: improve comments

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This commit is contained in:
Felix Lange 2025-09-05 14:33:53 +02:00
parent f8b8610d6d
commit 3932b1ca35
1 changed files with 4 additions and 4 deletions
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8
core/vm/contracts.go
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@ -396,24 +396,24 @@ func byzantiumMultComplexity(x uint64) uint64 {
case x <= 1024: case x <= 1024:
// x^2 / 4 + 96*x - 3072 // x^2 / 4 + 96*x - 3072
return x*x/4 + 96*x - 3072 return x*x/4 + 96*x - 3072
default: default:
// For large x, use uint256 arithmetic to avoid overflow // For large x, use uint256 arithmetic to avoid overflow
// x^2 / 16 + 480*x - 199680 // x^2 / 16 + 480*x - 199680
// xSqr = x^2
// xSqr = x^2 / 16
carry, xSqr := bits.Mul64(x, x) carry, xSqr := bits.Mul64(x, x)
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64
} }
// Calculate x^2 / 16
xSqr = xSqr >> 4 xSqr = xSqr >> 4
// Calculate 480 * x (can't overflow if x^2 didn't overflow) // Calculate 480 * x (can't overflow if x^2 didn't overflow)
x480 := x * 480 x480 := x * 480
// Calculate 480 * x - 199680 (will not underflow, since x > 1024) // Calculate 480 * x - 199680 (will not underflow, since x > 1024)
x480 = x480 - 199680 x480 = x480 - 199680
// xSqr + x480
sum, carry := bits.Add64(xSqr, x480, 0) sum, carry := bits.Add64(xSqr, x480, 0)
if carry != 0 { if carry != 0 {
return math.MaxUint64 return math.MaxUint64