2023-10-19 14:31:46 CST W42D4

ffmpeg_helper.go

@@ -5,6 +5,7 @@ package ffmpeg
 */
 import "C"
 import (
+	"reflect"
 	"unsafe"
 )
 
@@ -31,12 +32,69 @@ func StringCasting(str string) (allocPtr *C.char, freeFunc func()) {
 	return allocPtr, freeFunc
 }
 
-// SliceWithOffset returns a []byte slice from a porinter with size.
-func Slice[T HelperInteger](data *uint8, size T) []byte {
-	return unsafe.Slice(data, size)
+// SliceWithOffset returns a []byte slice from a porinter with offset and size.
+func ByteSliceWithOffset[X any, Y, Z HelperInteger](data *X, offset Y, size Z) []byte {
+	return unsafe.Slice((*byte)(unsafe.Add(unsafe.Pointer(uintptr(unsafe.Pointer(data))), offset)), size)
 }
 
-// SliceWithOffset returns a []byte slice from a porinter with offset and size.
-func SliceWithOffset[U, V HelperInteger](data *uint8, offset U, size V) []byte {
-	return unsafe.Slice((*uint8)(unsafe.Add(unsafe.Pointer(uintptr(unsafe.Pointer(data))), offset)), size)
+// Slice returns a []byte slice from a porinter with size.
+func ByteSlice[U any, V HelperInteger](data *U, size V) []byte {
+	return ByteSliceWithOffset(data, 0, size)
+}
+
+// PointerOffset offset the pointer point.
+func PointerOffset[U any, V HelperInteger](ptr *U, offset V) *U {
+	if ptr == nil {
+		return nil
+	}
+	return (*U)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) +
+		uintptr(unsafe.Sizeof(*ptr))*(uintptr(offset))))
+}
+
+// TruncSlice return a slice from a sign-terminated array.
+func TruncSlice[T any](ptr *T, fn func(T) bool) []T {
+	if ptr == nil {
+		return nil
+	}
+	for i := 0; ; i++ {
+		if fn(*(*T)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) +
+			uintptr(unsafe.Sizeof(*ptr))*uintptr(i)))) {
+			return unsafe.Slice(ptr, i)
+		}
+	}
+}
+
+// TruncStringSlice returns a string slice from a NULL-terminated *C.char array.
+func TruncStringSlice(ptr **C.char) (v []string) {
+	if ptr == nil {
+		return nil
+	}
+	for *ptr != nil && **ptr != C.char(0x00) {
+		v = append(v, C.GoString(*ptr))
+		ptr = (**C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) +
+			uintptr(unsafe.Sizeof(*ptr))))
+	}
+	return v
+}
+
+// CVoidPointer represents a (void*) type pointer in the C world.
+type CVoidPointer any
+
+// VoidPointer returns a unsafe.Pointer from CVoidPointer.
+func VoidPointer(a CVoidPointer) unsafe.Pointer {
+	if a == nil {
+		return nil
+	}
+	return unsafe.Pointer(reflect.ValueOf(a).Pointer())
+}
+
+// CVoidPointer represents a (void**) type pointer in the C world.
+type CVoidPointerPointer any
+
+// VoidPointerPointer returns a *unsafe.Pointer from CVoidPointerPointer.
+func VoidPointerPointer(a CVoidPointerPointer) *unsafe.Pointer {
+	if a == nil {
+		return nil
+	}
+	return (*unsafe.Pointer)(unsafe.Pointer(reflect.ValueOf(a).Pointer()))
 }