diff options
Diffstat (limited to 'src/runtime/string1.go')
-rw-r--r-- | src/runtime/string1.go | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/runtime/string1.go b/src/runtime/string1.go new file mode 100644 index 000000000..35cde43be --- /dev/null +++ b/src/runtime/string1.go @@ -0,0 +1,108 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime + +import "unsafe" + +//go:nosplit +func findnull(s *byte) int { + if s == nil { + return 0 + } + p := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s)) + l := 0 + for p[l] != 0 { + l++ + } + return l +} + +func findnullw(s *uint16) int { + if s == nil { + return 0 + } + p := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(s)) + l := 0 + for p[l] != 0 { + l++ + } + return l +} + +var maxstring uintptr = 256 // a hint for print + +//go:nosplit +func gostringnocopy(str *byte) string { + var s string + sp := (*stringStruct)(unsafe.Pointer(&s)) + sp.str = unsafe.Pointer(str) + sp.len = findnull(str) + for { + ms := maxstring + if uintptr(len(s)) <= ms || casuintptr(&maxstring, ms, uintptr(len(s))) { + break + } + } + return s +} + +func gostringw(strw *uint16) string { + var buf [8]byte + str := (*[_MaxMem/2/2 - 1]uint16)(unsafe.Pointer(strw)) + n1 := 0 + for i := 0; str[i] != 0; i++ { + n1 += runetochar(buf[:], rune(str[i])) + } + s, b := rawstring(n1 + 4) + n2 := 0 + for i := 0; str[i] != 0; i++ { + // check for race + if n2 >= n1 { + break + } + n2 += runetochar(b[n2:], rune(str[i])) + } + b[n2] = 0 // for luck + return s[:n2] +} + +func strcmp(s1, s2 *byte) int32 { + p1 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s1)) + p2 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s2)) + + for i := uintptr(0); ; i++ { + c1 := p1[i] + c2 := p2[i] + if c1 < c2 { + return -1 + } + if c1 > c2 { + return +1 + } + if c1 == 0 { + return 0 + } + } +} + +func strncmp(s1, s2 *byte, n uintptr) int32 { + p1 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s1)) + p2 := (*[_MaxMem/2 - 1]byte)(unsafe.Pointer(s2)) + + for i := uintptr(0); i < n; i++ { + c1 := p1[i] + c2 := p2[i] + if c1 < c2 { + return -1 + } + if c1 > c2 { + return +1 + } + if c1 == 0 { + break + } + } + return 0 +} |