From 915fff96f84c79f480f128d572ee54ffa6a00ad4 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Wed, 9 Nov 2022 12:51:02 +0900
Subject: [PATCH] all: reduce reflect usages

---
 .../graphicsdriver/directx/api_windows.go     |  9 ++---
 .../graphicsdriver/opengl/gl/conversions.go   | 15 +------
 .../opengl/gl/conversions_cgo.go              | 12 +++---
 .../opengl/gl/conversions_nocgo.go            | 39 ++++++++++---------
 4 files changed, 31 insertions(+), 44 deletions(-)

diff --git a/internal/graphicsdriver/directx/api_windows.go b/internal/graphicsdriver/directx/api_windows.go
index 577ace3bb..fcf7c8721 100644
--- a/internal/graphicsdriver/directx/api_windows.go
+++ b/internal/graphicsdriver/directx/api_windows.go
@@ -17,7 +17,6 @@ package directx
 import (
 	"fmt"
 	"math"
-	"reflect"
 	"runtime"
 	"syscall"
 	"unsafe"
@@ -2294,11 +2293,9 @@ func (i *_ID3DBlob) Release() uint32 {
 }
 
 func (i *_ID3DBlob) String() string {
-	var str string
-	h := (*reflect.StringHeader)(unsafe.Pointer(&str))
-	h.Data = i.GetBufferPointer()
-	h.Len = int(i.GetBufferSize())
-	return str
+	bs := make([]byte, int(i.GetBufferSize()))
+	copy(bs, unsafe.Slice((*byte)(unsafe.Pointer(i.GetBufferPointer())), i.GetBufferSize()))
+	return string(bs)
 }
 
 type _IDXGIAdapter struct {
diff --git a/internal/graphicsdriver/opengl/gl/conversions.go b/internal/graphicsdriver/opengl/gl/conversions.go
index e9c1a5f74..0401a99d2 100644
--- a/internal/graphicsdriver/opengl/gl/conversions.go
+++ b/internal/graphicsdriver/opengl/gl/conversions.go
@@ -4,8 +4,6 @@ package gl
 
 import (
 	"fmt"
-	"reflect"
-	"strings"
 	"unsafe"
 )
 
@@ -14,7 +12,7 @@ import (
 //
 // For example:
 //
-//	var data []uint8
+//	var data []byte
 //	...
 //	gl.TexImage2D(glconst.TEXTURE_2D, ..., glconst.UNSIGNED_BYTE, gl.Ptr(&data[0]))
 func Ptr(data any) unsafe.Pointer {
@@ -40,14 +38,3 @@ func Ptr(data any) unsafe.Pointer {
 	}
 	return addr
 }
-
-// Str takes a null-terminated Go string and returns its GL-compatible address.
-// This function reaches into Go string storage in an unsafe way so the caller
-// must ensure the string is not garbage collected.
-func Str(str string) *uint8 {
-	if !strings.HasSuffix(str, "\x00") {
-		panic("str argument missing null terminator: " + str)
-	}
-	header := (*reflect.StringHeader)(unsafe.Pointer(&str))
-	return (*uint8)(unsafe.Pointer(header.Data))
-}
diff --git a/internal/graphicsdriver/opengl/gl/conversions_cgo.go b/internal/graphicsdriver/opengl/gl/conversions_cgo.go
index a2fc88c06..87aa0375e 100644
--- a/internal/graphicsdriver/opengl/gl/conversions_cgo.go
+++ b/internal/graphicsdriver/opengl/gl/conversions_cgo.go
@@ -13,7 +13,7 @@ import "C"
 
 // GoStr takes a null-terminated string returned by OpenGL and constructs a
 // corresponding Go string.
-func GoStr(cstr *uint8) string {
+func GoStr(cstr *byte) string {
 	return C.GoString((*C.char)(unsafe.Pointer(cstr)))
 }
 
@@ -24,18 +24,18 @@ func GoStr(cstr *uint8) string {
 // in order to free the memory.
 //
 // If no strings are provided as a parameter this function will panic.
-func Strs(strs ...string) (cstrs **uint8, free func()) {
+func Strs(strs ...string) (cstrs **byte, free func()) {
 	if len(strs) == 0 {
-		panic("Strs: expected at least 1 string")
+		panic("gl: expected at least 1 string at Strs")
 	}
 
-	css := make([]*uint8, 0, len(strs))
+	css := make([]*byte, 0, len(strs))
 	for _, str := range strs {
 		cs := C.CString(str)
-		css = append(css, (*uint8)(unsafe.Pointer(cs)))
+		css = append(css, (*byte)(unsafe.Pointer(cs)))
 	}
 
-	return (**uint8)(&css[0]), func() {
+	return (**byte)(&css[0]), func() {
 		for _, cs := range css {
 			C.free(unsafe.Pointer(cs))
 		}
diff --git a/internal/graphicsdriver/opengl/gl/conversions_nocgo.go b/internal/graphicsdriver/opengl/gl/conversions_nocgo.go
index cf8bf3ddd..c878c8d90 100644
--- a/internal/graphicsdriver/opengl/gl/conversions_nocgo.go
+++ b/internal/graphicsdriver/opengl/gl/conversions_nocgo.go
@@ -6,22 +6,24 @@ package gl
 
 import (
 	"runtime"
-	"strings"
 	"unsafe"
 )
 
 // GoStr takes a null-terminated string returned by OpenGL and constructs a
 // corresponding Go string.
-func GoStr(cstr *uint8) string {
-	str := ""
-	for {
-		if *cstr == 0 {
-			break
-		}
-		str += string(*cstr)
-		cstr = (*uint8)(unsafe.Pointer(uintptr(unsafe.Pointer(cstr)) + 1))
+func GoStr(cstr *byte) string {
+	if cstr == nil {
+		return ""
 	}
-	return str
+	x := unsafe.Slice(cstr, 1e9)
+	for i, c := range x {
+		if c == 0 {
+			str := make([]byte, i)
+			copy(str, x[:i])
+			return string(str)
+		}
+	}
+	return ""
 }
 
 // Strs takes a list of Go strings (with or without null-termination) and
@@ -31,19 +33,20 @@ func GoStr(cstr *uint8) string {
 // in order to free the memory.
 //
 // If no strings are provided as a parameter this function will panic.
-func Strs(strs ...string) (cstrs **uint8, free func()) {
+func Strs(strs ...string) (cstrs **byte, free func()) {
 	if len(strs) == 0 {
-		panic("Strs: expected at least 1 string")
+		panic("gl: expected at least 1 string at Strs")
 	}
 
-	var pinned []string
-	var ptrs []*uint8
+	pinned := make([][]byte, 0, len(strs))
+	ptrs := make([]*byte, 0, len(strs))
 	for _, str := range strs {
-		if !strings.HasSuffix(str, "\x00") {
-			str += "\x00"
+		bs := []byte(str)
+		if len(bs) == 0 || bs[len(bs)-1] != 0 {
+			bs = append(bs, 0)
 		}
-		pinned = append(pinned, str)
-		ptrs = append(ptrs, Str(str))
+		pinned = append(pinned, bs)
+		ptrs = append(ptrs, &bs[0])
 	}
 
 	return &ptrs[0], func() {