150 lines
3.8 KiB
Go
150 lines
3.8 KiB
Go
/*
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* Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package runtime
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import (
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"unsafe"
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"github.com/goplus/llgo/c"
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"github.com/goplus/llgo/internal/abi"
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"github.com/goplus/llgo/internal/runtime/math"
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)
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// -----------------------------------------------------------------------------
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// Slice is the runtime representation of a slice.
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type Slice struct {
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data unsafe.Pointer
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len int
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cap int
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}
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func NewSlice3(base unsafe.Pointer, eltSize, cap, i, j, k int) (s Slice) {
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if i < 0 || j < i || k < j || k > cap {
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panic("slice index out of bounds")
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}
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s.len = j - i
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s.cap = k - i
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if k-i > 0 {
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s.data = c.Advance(base, i*eltSize)
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} else {
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s.data = base
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}
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return
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}
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// SliceAppend append elem data and returns a slice.
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func SliceAppend(src Slice, data unsafe.Pointer, num, etSize int) Slice {
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if etSize == 0 {
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return src
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}
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oldLen := src.len
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src = GrowSlice(src, num, etSize)
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c.Memcpy(c.Advance(src.data, oldLen*etSize), data, uintptr(num*etSize))
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return src
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}
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// GrowSlice grows slice and returns the grown slice.
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func GrowSlice(src Slice, num, etSize int) Slice {
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oldLen := src.len
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newLen := oldLen + num
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if newLen > src.cap {
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newCap := nextslicecap(newLen, src.cap)
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p := AllocZ(uintptr(newCap * etSize))
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if oldLen != 0 {
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c.Memcpy(p, src.data, uintptr(oldLen*etSize))
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}
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src.data = p
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src.cap = newCap
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}
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src.len = newLen
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return src
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}
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// nextslicecap computes the next appropriate slice length.
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func nextslicecap(newLen, oldCap int) int {
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newcap := oldCap
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doublecap := newcap + newcap
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if newLen > doublecap {
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return newLen
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}
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const threshold = 256
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if oldCap < threshold {
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return doublecap
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}
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for {
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// Transition from growing 2x for small slices
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// to growing 1.25x for large slices. This formula
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// gives a smooth-ish transition between the two.
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newcap += (newcap + 3*threshold) >> 2
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// We need to check `newcap >= newLen` and whether `newcap` overflowed.
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// newLen is guaranteed to be larger than zero, hence
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// when newcap overflows then `uint(newcap) > uint(newLen)`.
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// This allows to check for both with the same comparison.
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if uint(newcap) >= uint(newLen) {
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break
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}
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}
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// Set newcap to the requested cap when
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// the newcap calculation overflowed.
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if newcap <= 0 {
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return newLen
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}
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return newcap
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}
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// SliceCopy copy data to slice and returns a slice.
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func SliceCopy(dst Slice, data unsafe.Pointer, num int, etSize int) int {
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n := dst.len
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if n > num {
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n = num
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}
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if n > 0 {
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c.Memmove(dst.data, data, uintptr(n*etSize))
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}
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return n
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}
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func MakeSlice(len, cap int, etSize int) Slice {
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mem, overflow := math.MulUintptr(uintptr(etSize), uintptr(cap))
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if overflow || mem > maxAlloc || len < 0 || len > cap {
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mem, overflow := math.MulUintptr(uintptr(etSize), uintptr(len))
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if overflow || mem > maxAlloc || len < 0 {
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panicmakeslicelen()
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}
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panicmakeslicecap()
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}
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return Slice{AllocZ(mem), len, cap}
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}
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func panicmakeslicelen() {
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panic(errorString("makeslice: len out of range"))
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}
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func panicmakeslicecap() {
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panic(errorString("makeslice: cap out of range"))
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}
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func SliceClear(t *abi.SliceType, s Slice) {
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c.Memset(s.data, 0, uintptr(s.len)*t.Elem.Size())
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}
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// -----------------------------------------------------------------------------
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