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Adjust Second constructor
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@qntm
qntm committed Jul 20, 2024
1 parent bddd49d commit 4dab5d0
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Showing 8 changed files with 306 additions and 319 deletions.
10 changes: 5 additions & 5 deletions src/munge.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ export const MODELS = {
}

const NOV = 10
const secondsPerDay = new Second(86_400n, 1n)
const secondsPerDay = new Second(new Rat(86_400n, 1n))
const mjdEpoch = {
unix: Second.fromMillis(Date.UTC(1858, NOV, 17))
}
Expand Down Expand Up @@ -63,20 +63,20 @@ export const munge = (data, model) => {
// Convert from a floating point number to a precise ratio
// Offsets are given in TAI seconds to seven decimal places, e.g. `1.422_818_0`.
// So we have to do some rounding
offsetAtRoot.atomic = new Second(
offsetAtRoot.atomic = new Second(new Rat(
BigInt(Math.round(offsetAtRoot.atomicFloat * 10_000_000)),
BigInt(10_000_000)
)
))

root.unix = mjdEpoch.unix.plusS(secondsPerDay.timesR(new Rat(BigInt(root.mjds))))

// Convert from a floating point number to a precise ratio
// Drift rates are given in TAI seconds to seven decimal places, e.g. `0.001_123_2`
// So we have to do some rounding
driftRate.atomicPerUnixDay = new Second(
driftRate.atomicPerUnixDay = new Second(new Rat(
BigInt(Math.round(driftRate.atomicPerUnixDayFloat * 10_000_000)),
BigInt(10_000_000)
)
))
driftRate.atomicPerUnix = driftRate.atomicPerUnixDay.divideS(secondsPerDay)

const slope = {}
Expand Down
2 changes: 1 addition & 1 deletion src/rat.js
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@ export class Rat {
const g2 = (de < 0) === (g < 0) ? g : -g

this.nu = nu / g2 // sign of `this.nu` is the sign of the represented rational
this.de = de / g2 // non-negative
this.de = de / g2 // positive
}

plus (other) {
Expand Down
18 changes: 7 additions & 11 deletions src/second.js
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Original file line number Diff line number Diff line change
@@ -1,28 +1,24 @@
import { Rat } from './rat.js'

export class Second {
constructor (nu, de) {
this.rat = new Rat(nu, de)
constructor (rat) {
this.rat = rat
}

plusS (other) {
const sum = this.rat.plus(other.rat)
return new Second(sum.nu, sum.de)
return new Second(this.rat.plus(other.rat))
}

minusS (other) {
const difference = this.rat.minus(other.rat)
return new Second(difference.nu, difference.de)
return new Second(this.rat.minus(other.rat))
}

timesR (other) {
const product = this.rat.times(other)
return new Second(product.nu, product.de)
return new Second(this.rat.times(other))
}

divideR (other) {
const quotient = this.rat.divide(other)
return new Second(quotient.nu, quotient.de)
return new Second(this.rat.divide(other))
}

divideS (other) {
Expand Down Expand Up @@ -51,7 +47,7 @@ Second.fromMillis = millis => {
throw Error(`Not an integer: ${millis}`)
}

return new Second(BigInt(millis), 1_000n)
return new Second(new Rat(BigInt(millis), 1_000n))
}

Second.END_OF_TIME = Symbol('end of time')
25 changes: 13 additions & 12 deletions test/converter.spec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import { describe, it } from 'mocha'
import { Converter } from '../src/converter.js'
import { MODELS } from '../src/munge.js'
import { Range } from '../src/range.js'
import { Rat } from '../src/rat.js'
import { Second } from '../src/second.js'

const JAN = 0
Expand Down Expand Up @@ -267,7 +268,7 @@ describe('Converter', () => {
])
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1))),
[
new Range(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).plusS(new Second(1n, 86_400_000n)))
new Range(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).plusS(new Second(new Rat(1n, 86_400_000n))))
])

// SMEAR MIDPOINT
Expand All @@ -279,7 +280,7 @@ describe('Converter', () => {
// SMEAR ENDS, ATOMIC IS A FULL SECOND AHEAD (actually Unix is a full second behind)
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999))),
[
new Range(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999)).plusS(new Second(86_399_999n, 86_400_000n)))
new Range(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999)).plusS(new Second(new Rat(86_399_999n, 86_400_000n))))
])
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 0))),
[
Expand All @@ -301,15 +302,15 @@ describe('Converter', () => {
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 0))),
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 0)))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1))),
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).minusS(new Second(1n, 86_401_000n)))
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).minusS(new Second(new Rat(1n, 86_401_000n))))

// SMEAR MIDPOINT
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 0, 0, 0, 500))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 0, 0, 0, 0)))

// SMEAR ENDS, UNIX HAS DROPPED A FULL SECOND BEHIND
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 999))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 999)).minusS(new Second(86_400_999n, 86_401_000n)))
Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 999)).minusS(new Second(new Rat(86_400_999n, 86_401_000n))))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 1, 0))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 0)))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 1, 1))),
Expand Down Expand Up @@ -482,7 +483,7 @@ describe('Converter', () => {
])
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1))),
[
new Range(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).minusS(new Second(1n, 86_400_000n)))
new Range(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).minusS(new Second(new Rat(1n, 86_400_000n))))
])

// SMEAR MIDPOINT
Expand All @@ -494,7 +495,7 @@ describe('Converter', () => {
// SMEAR ENDS, ATOMIC IS A FULL SECOND BEHIND (actually Unix is a full second ahead)
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999))),
[
new Range(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999)).minusS(new Second(86_399_999n, 86_400_000n)))
new Range(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 999)).minusS(new Second(new Rat(86_399_999n, 86_400_000n))))
])
assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 0))),
[
Expand All @@ -516,15 +517,15 @@ describe('Converter', () => {
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 0))),
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 0)))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1))),
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).plusS(new Second(1n, 86_399_000n)))
Second.fromMillis(Date.UTC(1979, DEC, 31, 12, 0, 0, 1)).plusS(new Second(new Rat(1n, 86_399_000n))))

// SMEAR MIDPOINT
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1979, DEC, 31, 23, 59, 59, 500))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 0, 0, 0, 0)))

// SMEAR ENDS, UNIX HAS RUN A FULL SECOND FASTER THAN ATOMIC
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 58, 999))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 58, 999)).plusS(new Second(86_398_999n, 86_399_000n)))
Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 58, 999)).plusS(new Second(new Rat(86_398_999n, 86_399_000n))))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 0))),
Second.fromMillis(Date.UTC(1980, JAN, 1, 12, 0, 0, 0)))
assert.deepStrictEqual(converter.atomicToUnix(Second.fromMillis(Date.UTC(1980, JAN, 1, 11, 59, 59, 1))),
Expand All @@ -543,9 +544,9 @@ describe('Converter', () => {

assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(1)),
[
new Range(new Second(900n, 1_000_000n))
new Range(new Second(new Rat(900n, 1_000_000n)))
])
assert.deepStrictEqual(converter.atomicToUnix(new Second(900n, 1_000_000n)),
assert.deepStrictEqual(converter.atomicToUnix(new Second(new Rat(900n, 1_000_000n))),
Second.fromMillis(1))
})

Expand All @@ -558,9 +559,9 @@ describe('Converter', () => {

assert.deepStrictEqual(converter.unixToAtomic(Second.fromMillis(-1)),
[
new Range(new Second(-900n, 1_000_000n))
new Range(new Second(new Rat(-900n, 1_000_000n)))
])
assert.deepStrictEqual(converter.atomicToUnix(new Second(-900n, 1_000_000n)),
assert.deepStrictEqual(converter.atomicToUnix(new Second(new Rat(-900n, 1_000_000n))),
Second.fromMillis(-1))
})
})
Expand Down
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