made linking with libc the default, as it's the most commonly used mode

Makefile

@@ -16,15 +16,17 @@ ifeq ($(sys), mingw)
 	alib = libminiglut-w32.a
 	bin = test.exe
 
+	# on windows/mingw we can build without linking to libc
+	CFLAGS += -DMINIGLUT_NO_LIBC
 	LDFLAGS = -mconsole -lopengl32 -lgdi32 -lwinmm
 else
 	ifeq ($(sys)-$(isx86), Linux-x86)
-		CFLAGS += -I/usr/X11R6/include
+		# for Linux x86/x86-64 we can build without linking to libc
+		CFLAGS += -I/usr/X11R6/include -DMINIGLUT_NO_LIBC
 		LDFLAGS = -L/usr/X11R6/lib -lX11 -lGL
 	else
 		# for other UNIX or non-x86 where sys_ and trig functions are not
 		# implemented, just use libc
-		CFLAGS += -DMINIGLUT_USE_LIBC
 		LDFLAGS = -lX11 -lGL -lm
 		ifeq ($(sys), IRIX)
 			CC = gcc

README.md

@@ -24,9 +24,12 @@ A second reason to use MiniGLUT is to ease porting of UNIX OpenGL programs to
 Windows, especially when using the microsoft compiler, where setting up and
 linking with a proper 3rd-party library is an ordeal in itself.  Even more so if
 you decide to statically link, at which point you need to deal with the whole
-"MSVC runtime" chaos. Even if you decide to link MiniGLUT as a static library,
-instead of dropping it in your code, it still won't present any MSVC runtime
-compatibility issues, since it doesn't call any C library functions whatsoever.
+"MSVC runtime" chaos.
+
+On GNU/Linux x86/x86-64 and 32bit Windows, MiniGLUT can be compiled to never
+call any C library functions whatsoever (which is the default if you use the
+included makefile/msvc project to build a static library). This is useful to
+avoid dependencies on any specific libc or msvc runtime.
 
 Download
 --------
@@ -50,15 +53,27 @@ When building with MSVC, linking with the correct libraries is taken care by
 pragmas in the header file. If you wish to avoid the winmm dependency, define
 `MINIGLUT_NO_WINMM`.
 
+To disable calling any C library functions, make sure to have `MINIGLUT_NO_LIBC`
+defined when building `miniglut.c`. Either add that to your build system, or
+just modify `miniglut.c` and define it at the top.
+
+> Note: in previous versions (including v0.5), building without libc was the
+> default, and you had to define `MINIGLUT_USE_LIBC` to make it use libc. But
+> it turns out usually when you're building miniglut as part of your project,
+> there's no real downside to using libc in most use cases, so I decided to
+> change the default, and have the extra define go to the static library build
+> files instead of *every* project which drops `miniglut.h`/`miniglut.c` in the
+> source tree.
+
 To avoid calling C library functions, MiniGLUT uses inline assembly code for
-system calls and trigonometric operations. This makes the default build
-incompatible with non-x86 systems, and with MSVC x64 builds. If you don't mind
-linking with the C library, you can define `MINIGLUT_USE_LIBC` to lift these
-limitations.
+system calls and trigonometric operations. This is currently implemented only
+on x86 (32 and 64bit), and only on 32bit when building with MSVC (which doesn't
+support inline assembly on x86-64). For all other systems you need to link with
+libc.
 
 License
 -------
-Copyright (C) 2020-2022 John Tsiombikas <[email protected]>
+Copyright (C) 2020-2024 John Tsiombikas <[email protected]>
 
 MiniGLUT is free software. Feel free to use, modify and/or redistribute it,
 under the terms of the GNU General Public License v3, or at your option any
@@ -74,6 +89,19 @@ To learn more about GPL-incompatible free software licenses where this might
 be an issue, see:
 https://www.gnu.org/licenses/license-list.en.html#GPLIncompatibleLicenses
 
+Implementation Notes
+--------------------
+On UNIX systems, spaceball callbacks are supported by talking to a 6dof device
+driver through the *Magellan X11 ClientMessage protocol*. This works with
+either the free software *spacenavd* driver, or the proprietary *3dxsrv*.
+Spacenavd supports all 6dof devices from the first serial ones to current
+models.
+
+On Windows, spaceball support relies on the 3Dconnexion driver and its old
+siapp API. This should work on any version of the driver from very old ones
+running on windows 9x and supporting serial devices, to the latest current
+driver for USB and bluetooth spacemice.
+
 Known Issues
 ------------
 MiniGLUT being a subset of GLUT, is missing a number of features. Some of them

miniglut.c

@@ -1,6 +1,6 @@
 /*
 MiniGLUT - minimal GLUT subset without dependencies
-Copyright (C) 2020-2022  John Tsiombikas <[email protected]>
+Copyright (C) 2020-2024  John Tsiombikas <[email protected]>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -2109,7 +2109,7 @@ static int handle_6dof(MSG* msg)
 #if defined(unix) || defined(__unix__) || defined(__APPLE__)
 #include <sys/time.h>
 
-#ifdef MINIGLUT_USE_LIBC
+#ifndef MINIGLUT_NO_LIBC
 #define sys_gettimeofday(tv, tz)	gettimeofday(tv, tz)
 #else
 static int sys_gettimeofday(struct timeval *tv, struct timezone *tz);
@@ -2156,7 +2156,7 @@ static void panic(const char *msg)
 }
 
 
-#ifdef MINIGLUT_USE_LIBC
+#ifndef MINIGLUT_NO_LIBC
 #include <stdlib.h>
 #ifdef _WIN32
 #include <io.h>
@@ -2174,7 +2174,7 @@ static int sys_write(int fd, const void *buf, int count)
 	return write(fd, buf, count);
 }
 
-#else	/* !MINIGLUT_USE_LIBC */
+#else	/* MINIGLUT_NO_LIBC */
 
 #ifdef __linux__
 #ifdef __x86_64__
@@ -2247,11 +2247,11 @@ static int sys_write(int fd, const void *buf, int count)
 	return wrsz;
 }
 #endif	/* _WIN32 */
-#endif	/* !MINIGLUT_USE_LIBC */
+#endif	/* MINIGLUT_NO_LIBC */
 
 
 /* ----------------- primitives ------------------ */
-#ifdef MINIGLUT_USE_LIBC
+#ifndef MINIGLUT_NO_LIBC
 #include <stdlib.h>
 #include <math.h>
 
@@ -2266,7 +2266,7 @@ float mglut_atan(float x)
 	return atan(x);
 }
 
-#else	/* !MINIGLUT_USE_LIBC */
+#else	/* MINIGLUT_NO_LIBC */
 
 #ifdef __GNUC__
 void mglut_sincos(float angle, float *sptr, float *cptr)
@@ -2339,7 +2339,7 @@ float mglut_atan(float x)
 	modify [8087];
 #endif	/* __WATCOMC__ */
 
-#endif	/* !MINIGLUT_USE_LIBC */
+#endif	/* MINIGLUT_NO_LIBC */
 
 #define PI	3.1415926536f
 

miniglut.h

@@ -1,6 +1,6 @@
 /*
 MiniGLUT - minimal GLUT subset without dependencies
-Copyright (C) 2020-2022  John Tsiombikas <[email protected]>
+Copyright (C) 2020-2024  John Tsiombikas <[email protected]>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by