b612
16c62a97d5
- 新增时标、ΔT 模型、质心时间与 UT1 支持 - 改进日月食、月掩、行星事件及路径边界计算 - 完善恒星三维自行与动态距离传播 - 扩展 SVG、GeoJSON、KML 输出与底层距离换算工具 - 整理中英文手册、示例资源及回归测试
86 lines
2.4 KiB
Go
86 lines
2.4 KiB
Go
package basic
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import (
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"math"
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"sync"
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"sync/atomic"
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)
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// 固定容量缓存以 ΔT 世代区分模型，RWMutex 保护宿主多线程访问。
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const siderealMemoBits = 14
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const siderealMemoSize = 1 << siderealMemoBits
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type siderealMemoEntry struct {
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key uint64
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value float64
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generation uint64
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}
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var (
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siderealMemoMu sync.RWMutex
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siderealMemoTable [siderealMemoSize]siderealMemoEntry
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siderealMemoHits uint64
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siderealMemoMisses uint64
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siderealMemoStores uint64
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)
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// siderealMemoIndex 用高低位混合避免相邻儒略日落在相邻槽位而互相驱逐。
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func siderealMemoIndex(jd float64) uint64 {
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bits := math.Float64bits(jd)
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return (bits ^ (bits >> 29)) & (siderealMemoSize - 1)
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}
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// siderealMemoLoad 返回缓存命中值；ΔT 世代不匹配时按未命中处理。
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func siderealMemoLoad(jd float64) (float64, bool) {
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generation := deltaTGenerationValue()
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entry := &siderealMemoTable[siderealMemoIndex(jd)]
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siderealMemoMu.RLock()
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key, value, entryGeneration := entry.key, entry.value, entry.generation
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siderealMemoMu.RUnlock()
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if entryGeneration == generation && key == math.Float64bits(jd) {
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atomic.AddUint64(&siderealMemoHits, 1)
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return value, true
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}
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atomic.AddUint64(&siderealMemoMisses, 1)
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return 0, false
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}
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// 世代须在求值前采样，防止旧模型结果被缓存为新模型结果。
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func siderealMemoStore(jd, value float64, generation uint64) {
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if deltaTGenerationValue() != generation {
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return
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}
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index := siderealMemoIndex(jd)
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siderealMemoMu.Lock()
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siderealMemoTable[index] = siderealMemoEntry{
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key: math.Float64bits(jd),
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value: value,
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generation: generation,
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}
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siderealMemoMu.Unlock()
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atomic.AddUint64(&siderealMemoStores, 1)
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}
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// siderealMemoGeneration 在求值前采样 ΔT 世代，供 siderealMemoStore 校验。
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func siderealMemoGeneration() uint64 {
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return deltaTGenerationValue()
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}
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// siderealMemoStats 返回命中/未命中/写入计数，供测试守护记忆表确实生效。
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func siderealMemoStats() (hits, misses, stores uint64) {
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return atomic.LoadUint64(&siderealMemoHits), atomic.LoadUint64(&siderealMemoMisses),
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atomic.LoadUint64(&siderealMemoStores)
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}
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func resetSiderealMemo() {
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siderealMemoMu.Lock()
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for i := range siderealMemoTable {
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siderealMemoTable[i] = siderealMemoEntry{}
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}
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siderealMemoMu.Unlock()
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atomic.StoreUint64(&siderealMemoHits, 0)
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atomic.StoreUint64(&siderealMemoMisses, 0)
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atomic.StoreUint64(&siderealMemoStores, 0)
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}
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