forked from mirror/ledisdb
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
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package lua
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import (
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"reflect"
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"unsafe"
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)
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// iface is an internal representation of the go-interface.
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type iface struct {
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itab unsafe.Pointer
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word unsafe.Pointer
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}
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const preloadLimit LNumber = 128
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var _fv float64
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var _uv uintptr
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// allocator is a fast bulk memory allocator for the LValue.
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type allocator struct {
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top int
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size int
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nptrs []LValue
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nheader *reflect.SliceHeader
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fptrs []float64
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fheader *reflect.SliceHeader
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itabLNumber unsafe.Pointer
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preloads [int(preloadLimit)]LValue
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}
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func newAllocator(size int) *allocator {
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al := &allocator{
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top: 0,
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size: size,
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nptrs: make([]LValue, size),
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nheader: nil,
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fptrs: make([]float64, size),
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fheader: nil,
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itabLNumber: unsafe.Pointer(nil),
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}
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al.nheader = (*reflect.SliceHeader)(unsafe.Pointer(&al.nptrs))
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al.fheader = (*reflect.SliceHeader)(unsafe.Pointer(&al.fptrs))
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var v LValue = LNumber(0)
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vp := (*iface)(unsafe.Pointer(&v))
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al.itabLNumber = vp.itab
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for i := 0; i < int(preloadLimit); i++ {
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al.preloads[i] = LNumber(i)
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}
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return al
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}
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func (al *allocator) LNumber2I(v LNumber) LValue {
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if v >= 0 && v < preloadLimit && float64(v) == float64(int64(v)) {
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return al.preloads[int(v)]
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}
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if al.top == len(al.nptrs)-1 {
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al.top = 0
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al.nptrs = make([]LValue, al.size)
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al.nheader = (*reflect.SliceHeader)(unsafe.Pointer(&al.nptrs))
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al.fptrs = make([]float64, al.size)
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al.fheader = (*reflect.SliceHeader)(unsafe.Pointer(&al.fptrs))
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}
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fptr := (*float64)(unsafe.Pointer(al.fheader.Data + uintptr(al.top)*unsafe.Sizeof(_fv)))
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e := *(*LValue)(unsafe.Pointer(al.nheader.Data + uintptr(al.top)*unsafe.Sizeof(_uv)))
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al.top++
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ep := (*iface)(unsafe.Pointer(&e))
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ep.itab = al.itabLNumber
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*fptr = float64(v)
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ep.word = unsafe.Pointer(fptr)
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return e
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}
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