Remove Cgo dependency on Windows

functions.go

@@ -1,6 +1,9 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 // A Function definition.
 type Function struct {
@@ -10,6 +13,34 @@ type Function struct {
 	Return     Type
 }
 
+// IsImplementedForSyscall returns a boolean value indicating whether the function is implemented for syscall or not.
+func (f Function) IsImplementedForSyscall() bool {
+	// As there is no syscall.Syscall18 or more, more than 15 arguments cannot be accepted.
+	// See https://github.com/golang/go/issues/28434.
+	if len(f.Parameters) > 15 {
+		return false
+	}
+	return true
+}
+
+// Syscall returns a syscall expression for Windows.
+func (f Function) Syscall() string {
+	var ps []string
+	for _, p := range f.Parameters {
+		ps = append(ps, p.Type.ConvertGoToUintptr(p.GoName()))
+	}
+	for len(ps) == 0 || len(ps)%3 != 0 {
+		ps = append(ps, "0")
+	}
+
+	post := ""
+	if len(ps) > 3 {
+		post = fmt.Sprintf("%d", len(ps))
+	}
+
+	return fmt.Sprintf("syscall.Syscall%s(gp%s, %d, %s)", post, f.GoName, len(f.Parameters), strings.Join(ps, ", "))
+}
+
 // A Parameter to a Function.
 type Parameter struct {
 	Name string

package.go

@@ -68,14 +68,26 @@ func (pkg *Package) GeneratePackage(dir string) error {
 	if err := pkg.generateFile("package", dir); err != nil {
 		return err
 	}
+	if err := pkg.generateFile("package_notwindows", dir); err != nil {
+		return err
+	}
+	if err := pkg.generateFile("package_windows", dir); err != nil {
+		return err
+	}
 	if err := pkg.generateFile("conversions", dir); err != nil {
 		return err
 	}
-	if err := pkg.generateFile("procaddr", dir); err != nil {
+	if err := pkg.generateFile("procaddr_notwindows", dir); err != nil {
+		return err
+	}
+	if err := pkg.generateFile("procaddr_windows", dir); err != nil {
 		return err
 	}
 	if pkg.HasDebugCallbackFeature() {
-		if err := pkg.generateFile("debug", dir); err != nil {
+		if err := pkg.generateFile("debug_notwindows", dir); err != nil {
+			return err
+		}
+		if err := pkg.generateFile("debug_windows", dir); err != nil {
 			return err
 		}
 	}

tmpl/conversions.tmpl

@@ -6,13 +6,11 @@ package {{.Name}}
 import (
 	"fmt"
 	"reflect"
+	"runtime"
 	"strings"
 	"unsafe"
 )
 
-// #include <stdlib.h>
-import "C"
-
 // Ptr takes a slice or pointer (to a singular scalar value or the first
 // element of an array or slice) and returns its GL-compatible address.
 //
@@ -70,7 +68,15 @@ func Str(str string) *uint8 {
 // GoStr takes a null-terminated string returned by OpenGL and constructs a
 // corresponding Go string.
 func GoStr(cstr *uint8) string {
-	return C.GoString((*C.char)(unsafe.Pointer(cstr)))
+	str := ""
+	for {
+		if *cstr == 0 {
+			break
+		}
+		str += string(*cstr)
+		cstr = (*uint8)(unsafe.Pointer(uintptr(unsafe.Pointer(cstr)) + 1))
+	}
+	return str
 }
 
 // Strs takes a list of Go strings (with or without null-termination) and
@@ -85,26 +91,18 @@ func Strs(strs ...string) (cstrs **uint8, free func()) {
 		panic("Strs: expected at least 1 string")
 	}
 
-	// Allocate a contiguous array large enough to hold all the strings' contents.
-	n := 0
-	for i := range strs {
-		n += len(strs[i])
+	var pinned []string
+	var ptrs []*uint8
+	for _, str := range strs {
+		if !strings.HasSuffix(str, "\x00") {
+			str += "\x00"
+		}
+		pinned = append(pinned, str)
+		ptrs = append(ptrs, Str(str))
 	}
-	data := C.malloc(C.size_t(n))
 
-	// Copy all the strings into data.
-	dataSlice := *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{
-		Data: uintptr(data),
-		Len:  n,
-		Cap:  n,
-	}))
-	css := make([]*uint8, len(strs)) // Populated with pointers to each string.
-	offset := 0
-	for i := range strs {
-		copy(dataSlice[offset:offset+len(strs[i])], strs[i][:]) // Copy strs[i] into proper data location.
-		css[i] = (*uint8)(unsafe.Pointer(&dataSlice[offset]))   // Set a pointer to it.
-		offset += len(strs[i])
+	return &ptrs[0], func() {
+		runtime.KeepAlive(pinned)
+		pinned = nil
 	}
-
-	return (**uint8)(&css[0]), func() { C.free(data) }
 }

tmpl/debug.tmpl → tmpl/debug_notwindows.tmpl

@@ -1,4 +1,6 @@
 //glow:keepspace
+// +build !windows
+
 // Code generated by glow (https://github.com/go-gl/glow). DO NOT EDIT.
 
 package {{.Name}}

tmpl/debug_windows.tmpl

@@ -0,0 +1,16 @@
+//glow:keepspace
+// Code generated by glow (https://github.com/go-gl/glow). DO NOT EDIT.
+
+package {{.Name}}
+//glow:rmspace
+
+import "unsafe"
+
+type DebugProc func(
+	source uint32,
+	gltype uint32,
+	id uint32,
+	severity uint32,
+	length int32,
+	message string,
+	userParam unsafe.Pointer)

tmpl/package.tmpl

@@ -18,95 +18,12 @@
 package {{.Name}}
 //glow:rmspace
 
-{{define "paramsCDecl"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.Type.CType}} {{$p.CName}}{{end}}{{end}}
-{{define "paramsCCall"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{if $p.Type.IsDebugProc}}glowCDebugCallback{{else}}{{$p.CName}}{{end}}{{end}}{{end}}
-
-{{define "paramsGoDecl"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.GoName}} {{$p.Type.GoType}}{{end}}{{end}}
-{{define "paramsGoCall"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.Type.ConvertGoToC $p.GoName}}{{end}}{{end}}
-
-// #cgo darwin        LDFLAGS: -framework OpenGL
-// #cgo linux freebsd LDFLAGS: -lGL
-// #cgo windows       LDFLAGS: -lopengl32
-//
-// #if defined(_WIN32) && !defined(APIENTRY) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__)
-// #ifndef WIN32_LEAN_AND_MEAN
-// #define WIN32_LEAN_AND_MEAN 1
-// #endif
-// #include <windows.h>
-// #endif
-//
-// #ifndef APIENTRY
-// #define APIENTRY
-// #endif
-// #ifndef APIENTRYP
-// #define APIENTRYP APIENTRY *
-// #endif
-// #ifndef GLAPI
-// #define GLAPI extern
-// #endif
-//
-// {{range .Typedefs}}
-// {{replace .CTypedef "\n" "\n// " -1}}
-// {{end}}
-//
-// {{if .HasDebugCallbackFeature}}
-// extern void glowDebugCallback_{{.UniqueName}}(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userParam);
-// static void APIENTRY glowCDebugCallback(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userParam) {
-//   glowDebugCallback_{{.UniqueName}}(source, type, id, severity, length, message, userParam);
-// }
-// {{end}}
-//
-// {{range .Functions}}
-// typedef {{.Return.CType}} (APIENTRYP GP{{toUpper .GoName}})({{template "paramsCDecl" .Parameters}});
-// {{end}}
-//
-// {{range .Functions}}
-// static {{.Return.CType}} glow{{.GoName}}(GP{{toUpper .GoName}} fnptr{{if ge (len .Parameters) 1}}, {{end}}{{template "paramsCDecl" .Parameters}}) {
-//   {{if not .Return.IsVoid}}return {{end}}(*fnptr)({{template "paramsCCall" .Parameters}});
-// }
-// {{end}}
-//
-import "C"
-import (
-  {{if .HasRequiredFunctions}}
-  "errors"
-  {{end}}
-  "unsafe"
-)
-
 const (
-  {{range .Enums}}
-  {{.GoName}} = {{.Value}}
-  {{end}}
-)
-
-var (
-  {{range .Functions}}
-  gp{{.GoName}} C.GP{{toUpper .GoName}}
-  {{end}}
+	{{range .Enums}}
+	{{.GoName}} = {{.Value}}
+	{{end}}
 )
 
-// Helper functions
-func boolToInt(b bool) int {
-	if b { return 1 }
-	return 0
-}
-
-{{define "bridgeCall"}}C.glow{{.GoName}}(gp{{.GoName}}{{if ge (len .Parameters) 1}}, {{end}}{{template "paramsGoCall" .Parameters}}){{end}}
-{{range .Functions}}
-{{.Comment}}
-func {{.GoName}}({{template "paramsGoDecl" .Parameters}}){{if not .Return.IsVoid}} {{.Return.GoType}}{{end}} {
-  {{range .Parameters}}
-  {{if .Type.IsDebugProc}}userDebugCallback = {{.GoName}}{{end}}
-  {{end}}
-  {{if .Return.IsVoid}}{{template "bridgeCall" .}}
-  {{else}}
-  ret := {{template "bridgeCall" .}}
-  return {{.Return.ConvertCToGo "ret"}}
-  {{end}}
-}
-{{end}}
-
 //glow:keepspace
 // Init initializes the OpenGL bindings by loading the function pointers (for
 // each OpenGL function) from the active OpenGL context.
@@ -131,18 +48,3 @@ func {{.GoName}}({{template "paramsGoDecl" .Parameters}}){{if not .Return.IsVoid
 func Init() error {
   return InitWithProcAddrFunc(getProcAddress)
 }
-
-// InitWithProcAddrFunc intializes the package using the specified OpenGL
-// function pointer loading function. For more cases Init should be used
-// instead.
-func InitWithProcAddrFunc(getProcAddr func(name string) unsafe.Pointer) error {
-  {{range .Functions}}
-  gp{{.GoName}} = (C.GP{{toUpper .GoName}})(getProcAddr("{{.Name}}"))
-  {{if .Required}}
-  if gp{{.GoName}} == nil {
-    return errors.New("{{.Name}}")
-  }
-  {{end}}
-  {{end}}
-	return nil
-}

tmpl/package_notwindows.tmpl

@@ -0,0 +1,106 @@
+//glow:keepspace
+// +build !windows
+
+// Code generated by glow (https://github.com/go-gl/glow). DO NOT EDIT.
+
+package {{.Name}}
+//glow:rmspace
+
+{{define "paramsCDecl"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.Type.CType}} {{$p.CName}}{{end}}{{end}}
+{{define "paramsCCall"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{if $p.Type.IsDebugProc}}glowCDebugCallback{{else}}{{$p.CName}}{{end}}{{end}}{{end}}
+
+{{define "paramsGoDecl"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.GoName}} {{$p.Type.GoType}}{{end}}{{end}}
+{{define "paramsGoCall"}}{{range $i, $p := .}}{{if ne $i 0}}, {{end}}{{$p.Type.ConvertGoToC $p.GoName}}{{end}}{{end}}
+
+// #cgo darwin        LDFLAGS: -framework OpenGL
+// #cgo linux freebsd LDFLAGS: -lGL
+// #cgo windows       LDFLAGS: -lopengl32
+//
+// #if defined(_WIN32) && !defined(APIENTRY) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__)
+// #ifndef WIN32_LEAN_AND_MEAN
+// #define WIN32_LEAN_AND_MEAN 1
+// #endif
+// #include <windows.h>
+// #endif
+//
+// #ifndef APIENTRY
+// #define APIENTRY
+// #endif
+// #ifndef APIENTRYP
+// #define APIENTRYP APIENTRY *
+// #endif
+// #ifndef GLAPI
+// #define GLAPI extern
+// #endif
+//
+// {{range .Typedefs}}
+// {{replace .CTypedef "\n" "\n// " -1}}
+// {{end}}
+//
+// {{if .HasDebugCallbackFeature}}
+// extern void glowDebugCallback_{{.UniqueName}}(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userParam);
+// static void APIENTRY glowCDebugCallback(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userParam) {
+//   glowDebugCallback_{{.UniqueName}}(source, type, id, severity, length, message, userParam);
+// }
+// {{end}}
+//
+// {{range .Functions}}
+// typedef {{.Return.CType}} (APIENTRYP GP{{toUpper .GoName}})({{template "paramsCDecl" .Parameters}});
+// {{end}}
+//
+// {{range .Functions}}
+// static {{.Return.CType}} glow{{.GoName}}(GP{{toUpper .GoName}} fnptr{{if ge (len .Parameters) 1}}, {{end}}{{template "paramsCDecl" .Parameters}}) {
+//   {{if not .Return.IsVoid}}return {{end}}(*fnptr)({{template "paramsCCall" .Parameters}});
+// }
+// {{end}}
+//
+import "C"
+import (
+	{{if .HasRequiredFunctions}}
+	"errors"
+	{{end}}
+	"unsafe"
+)
+
+var (
+	{{range .Functions}}
+	gp{{.GoName}} C.GP{{toUpper .GoName}}
+	{{end}}
+)
+
+// Helper functions
+func boolToInt(b bool) int {
+	if b { return 1 }
+	return 0
+}
+
+{{define "bridgeCall"}}C.glow{{.GoName}}(gp{{.GoName}}{{if ge (len .Parameters) 1}}, {{end}}{{template "paramsGoCall" .Parameters}}){{end}}
+{{range .Functions}}
+{{.Comment}}
+func {{.GoName}}({{template "paramsGoDecl" .Parameters}}){{if not .Return.IsVoid}} {{.Return.GoType}}{{end}} {
+	{{range .Parameters}}
+	{{if .Type.IsDebugProc}}userDebugCallback = {{.GoName}}{{end}}
+	{{end}}
+	{{if .Return.IsVoid}}{{template "bridgeCall" .}}
+	{{else}}
+	ret := {{template "bridgeCall" .}}
+	return {{.Return.ConvertCToGo "ret"}}
+	{{end}}
+}
+{{end}}
+
+
+// InitWithProcAddrFunc intializes the package using the specified OpenGL
+// function pointer loading function. For more cases Init should be used
+// instead.
+func InitWithProcAddrFunc(getProcAddr func(name string) unsafe.Pointer) error {
+	{{range .Functions}}
+	gp{{.GoName}} = (C.GP{{toUpper .GoName}})(getProcAddr("{{.Name}}"))
+	{{if .Required}}
+	if gp{{.GoName}} == nil {
+		return errors.New("{{.Name}}")
+	}
+	{{end}}
+	{{end}}
+	return nil
+}