func slice() {
fmt.Printf("Slice:\n")
var a [10]byte
// reflect.SliceHeader is a runtime representation of the internal workings
// of a slice. To make it point to a specific address, use something like
// the following:
// h.Data = uintptr(0x100)
// And replace '0x100' with the desired address.
var h reflect.SliceHeader
h.Data = uintptr(unsafe.Pointer(&a)) // The address of the first element of the underlying array.
h.Len = len(a)
h.Cap = len(a)
// Create an actual slice from the SliceHeader.
s := *(*[]byte)(unsafe.Pointer(&h))
fmt.Printf("Before:\n\ts: %v\n\ta: %v\n", s, a)
// Copy a string into the slice. This fills the underlying array, which in
// this case has been manually set to 'a'.
copy(s, "A string.")
fmt.Printf("After:\n\ts: %v\n\ta: %v\n", s, a)
}
func (repo *Repository) TagListMatch(pattern string) ([]string, error) {
cpattern := C.CString(pattern)
defer C.free(unsafe.Pointer(cpattern))
var ctags C.git_strarray
defer C.git_strarray_free(&ctags)
ecode := C.git_tag_list_match(&ctags, cpattern, repo.git_repository)
if ecode != git_SUCCESS {
return nil, gitError()
}
// TODO: Find a safer way if one exists.
var tagsSlice reflect.SliceHeader
length := int(ctags.count)
tagsSlice.Data = uintptr(unsafe.Pointer(ctags.strings))
tagsSlice.Len = length
tagsSlice.Cap = length
ctagStrings := *(*[]*C.char)(unsafe.Pointer(&tagsSlice))
tags := make([]string, length)
for i := 0; i < len(ctagStrings); i++ {
tags[i] = C.GoString(ctagStrings[i])
}
return tags, nil
}
func (repo *Repository) ListBranches(flags ...BranchType) ([]string, error) {
var cnames C.git_strarray
defer C.git_strarray_free(&cnames)
var cflags C.uint
if len(flags) == 0 {
cflags = C.uint(BRANCH_ALL)
} else {
for _, flag := range flags {
cflags |= C.uint(flag)
}
}
ecode := C.git_branch_list(&cnames, repo.git_repository, cflags)
if ecode != git_SUCCESS {
return nil, gitError()
}
// TODO: Find a safer way if one exists.
var namesSlice reflect.SliceHeader
length := int(cnames.count)
namesSlice.Data = uintptr(unsafe.Pointer(cnames.strings))
namesSlice.Len = length
namesSlice.Cap = length
cnameStrings := *(*[]*C.char)(unsafe.Pointer(&namesSlice))
names := make([]string, length)
for i := 0; i < len(cnameStrings); i++ {
names[i] = C.GoString(cnameStrings[i])
}
return names, nil
}
func GetKeyboardState() []uint8 {
var numkeys C.int
start := C.SDL_GetKeyboardState(&numkeys)
sh := reflect.SliceHeader{}
sh.Len = int(numkeys)
sh.Cap = int(numkeys)
sh.Data = uintptr(unsafe.Pointer(start))
return *(*[]uint8)(unsafe.Pointer(&sh))
}
func utf16slice(ptr *uint16) []uint16 {
hdr := reflect.SliceHeader{Data: uintptr(unsafe.Pointer(ptr)), Len: 1, Cap: 1}
slice := *((*[]uint16)(unsafe.Pointer(&hdr)))
i := 0
for slice[len(slice)-1] != 0 {
i++
}
hdr.Len = i
slice = *((*[]uint16)(unsafe.Pointer(&hdr)))
return slice
}
func init() {
data := new(reflect.SliceHeader)
data.Cap = 10
data.Len = 10
data.Data = uintptr(C.calloc(1, C.size_t(unsafe.Sizeof(SomeStruct{}))))
someData = *(*[]SomeStruct)(unsafe.Pointer(data))
for i := 0; i < len(someData); i++ {
someData[i] = SomeStruct{
Id: i,
Name: "你好" + strconv.Itoa(i),
}
}
}
func LoadWAV(file string) (*AudioSpec, []byte, error) {
cfile := C.CString(file)
defer C.free(unsafe.Pointer(cfile))
var a AudioSpec
var h reflect.SliceHeader
var l C.Uint32
if C.LoadWAV(cfile, a.c(), (**C.Uint8)(unsafe.Pointer(&h.Data)), &l) == nil {
return nil, nil, getError()
}
h.Len = int(l)
h.Cap = int(l)
return &a, *(*[]byte)(unsafe.Pointer(&h)), nil
}
func LoadWAV_RW(rw *RWops, free bool) (*AudioSpec, []byte, error) {
var cfree C.int
if free {
cfree = 1
}
var a AudioSpec
var h reflect.SliceHeader
var l C.Uint32
if C.SDL_LoadWAV_RW(rw.c, cfree, a.c(), (**C.Uint8)(unsafe.Pointer(&h.Data)), &l) == nil {
return nil, nil, getError()
}
h.Len = int(l)
h.Cap = int(l)
return &a, *(*[]byte)(unsafe.Pointer(&h)), nil
}
func (repo *Repository) ListReferences(flags RefType) ([]string, error) {
var crefs C.git_strarray
defer C.git_strarray_free(&crefs)
ecode := C.git_reference_list(&crefs, repo.git_repository, C.uint(flags))
if ecode != git_SUCCESS {
return nil, gitError()
}
// TODO: Find a safer way if one exists.
var refsSlice reflect.SliceHeader
length := int(crefs.count)
refsSlice.Data = uintptr(unsafe.Pointer(crefs.strings))
refsSlice.Len = length
refsSlice.Cap = length
crefStrings := *(*[]*C.char)(unsafe.Pointer(&refsSlice))
refs := make([]string, length)
for i := 0; i < len(crefStrings); i++ {
refs[i] = C.GoString(crefStrings[i])
}
return refs, nil
}
func (repo *Repository) GetManyAttrs(path string, names []string, flags ...AttrFlag) ([]string, error) {
var values [1]int8
cvalues := (*C.char)(&values[0])
cpath := C.CString(path)
defer C.free(unsafe.Pointer(cpath))
length := len(names)
clength := C.size_t(length)
cnames := make([]*C.char, length)
for i := 0; i < length; i++ {
cnames[i] = C.CString(names[i])
defer C.free(unsafe.Pointer(cnames[i]))
}
var cflags C.uint32_t
for _, flag := range flags {
cflags |= C.uint32_t(flag)
}
ecode := C.git_attr_get_many(&cvalues, repo.git_repository, cflags, cpath, clength, &cnames[0])
if ecode != git_SUCCESS {
return nil, gitError()
}
// TODO: Find a safer way if one exists.
var valuesSlice reflect.SliceHeader
valuesSlice.Data = uintptr(unsafe.Pointer(cvalues))
valuesSlice.Len = length
valuesSlice.Cap = length
cvalueStrings := *(*[]*C.char)(unsafe.Pointer(&valuesSlice))
valuesOut := make([]string, length)
for i := 0; i < length; i++ {
valuesOut[i] = C.GoString(cvalueStrings[i])
}
return valuesOut, nil
}
func main() {
data1 := initTestData()
checkTestData(len(data1), data1)
itemSize := unsafe.Sizeof(BigStruct{})
csize := C.size_t(itemSize * uintptr(len(data1)))
t1 := time.Now().Nanosecond()
mem := C.malloc(csize)
C.memcpy(mem, unsafe.Pointer((*reflect.SliceHeader)(unsafe.Pointer(&data1)).Data), csize)
t2 := time.Now().Nanosecond()
println("Go to C:", (t2-t1)/int(time.Microsecond))
data2 := new(reflect.SliceHeader)
data2.Cap = len(data1)
data2.Len = len(data1)
data2.Data = uintptr(mem)
checkTestData(len(data1), *(*[]BigStruct)(unsafe.Pointer(data2)))
t3 := time.Now().Nanosecond()
data3 := make([]BigStruct, len(data1))
copy(data3, *(*[]BigStruct)(unsafe.Pointer(data2)))
t4 := time.Now().Nanosecond()
checkTestData(len(data1), data3)
println("C to Go:", (t4-t3)/int(time.Microsecond))
}
func main() {
var a []byte
var e []byte
var r reflect.SliceHeader
fmt.Println("A", A)
a = A[2:10]
fmt.Println("a.cap", cap(a))
fmt.Println("a", a)
d := (unsafe.Pointer(&A))
fmt.Println("d", d)
r.Data = uintptr(unsafe.Pointer(&A))
r.Len = 4
r.Cap = 10
e = *(*[]byte)(unsafe.Pointer(&r))
//e = a
fmt.Println("e", e)
var rec Rec
f := unsafe.Sizeof(rec)
fmt.Println("sizeof rec", f)
/*
fmt.Println("A", A)
a := A[2:10]
fmt.Println("a", a)
b := unsafe.Pointer(&A)
fmt.Println("b", b)
c := unsafe.Pointer(&a)
fmt.Println("c", c)
d := (*[2]Rec)(unsafe.Pointer(&a[2]))
fmt.Println("d", d)
head := (* Head)(unsafe.Pointer(&A))
fmt.Println("head", head)
fmt.Println("*head", *head)
fmt.Println(unsafe.Sizeof(I))
fmt.Println(unsafe.Sizeof(leafhead))
fmt.Println(sizeHead)
*/
}
func NewFromFile(filename string) (*Continuum, error) {
var cont C.ketama_continuum
fn := C.CString(filename)
defer C.free(unsafe.Pointer(fn))
rv := C.ketama_roll(&cont, fn)
if rv == 0 {
errMsg := C.GoString(C.ketama_error())
return nil, errors.New(errMsg)
}
addrMap := make(map[string]net.Addr)
var mcsSlice reflect.SliceHeader
mcsSlice.Data = uintptr(cont.array)
mcsSlice.Len = int(cont.numpoints)
mcsSlice.Cap = int(cont.numpoints)
mcss := *(*[]C.mcs)(unsafe.Pointer(&mcsSlice))
for _, mcs := range mcss {
ip := C.GoString(C.get_ip(&mcs))
addrMap[ip], _ = getServerAddr(ip)
}
return &Continuum{&cont, addrMap}, nil
}
func setSlice(s *reflect.SliceHeader, data uintptr, n int) {
s.Data = data
s.Len = n
s.Cap = n
}
func setupSlice(hdr *reflect.SliceHeader, ptr unsafe.Pointer, size C.size_t) {
hdr.Cap = int(size)
hdr.Len = int(size)
hdr.Data = uintptr(ptr)
}
func newRawSliceHeader(sh *reflect.SliceHeader, b []byte, stride int) *reflect.SliceHeader {
sh.Len = len(b) / stride
sh.Cap = len(b) / stride
sh.Data = (uintptr)(unsafe.Pointer(&b[0]))
return sh
}