6257ddba78
The big change is that the GeoJSON package has been completely rewritten to fix a few of geometry calculation bugs, increase performance, and to better follow the GeoJSON spec RFC 7946. GeoJSON updates - A LineString now requires at least two points. - All json members, even foreign, now persist with the object. - The bbox member persists too but is no longer used for geometry calculations. This is change in behavior. Previously Tile38 would treat the bbox as the object's physical rectangle. - Corrections to geometry intersects and within calculations. Faster spatial queries - The performance of Point-in-polygon and object intersect operations are greatly improved for complex polygons and line strings. It went from O(n) to roughly O(log n). - The same for all collection types with many children, including FeatureCollection, GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon. Codebase changes - The pkg directory has been renamed to internal - The GeoJSON internal package has been moved to a seperate repo at https://github.com/tidwall/geojson. It's now vendored. Please look out for higher memory usage for datasets using complex shapes. A complex shape is one that has 64 or more points. For these shapes it's expected that there will be increase of least 54 bytes per point.
25 lines
630 B
Go
25 lines
630 B
Go
// +build amd64,go1.6
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package geohash
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// useAsm flag determines whether the assembly version of EncodeInt will be
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// used. By Default we fall back to encodeInt.
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var useAsm bool
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// cpuid executes the CPUID instruction to obtain processor identification and
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// feature information.
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func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
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// hasBMI2 returns whether the CPU supports Bit Manipulation Instruction Set
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// 2.
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func hasBMI2() bool {
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_, ebx, _, _ := cpuid(7, 0)
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return ebx&(1<<8) != 0
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}
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// init determines whether to use assembly version by performing CPU feature
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// check.
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func init() {
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useAsm = hasBMI2()
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}
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