[PATCH] ARM: Mes C Library: Support gcc-sans-libc.

[Danny Milosavljevic]

From: Jan Nieuwenhuizen <janneke@gnu.org>

* lib/linux/arm-mes-gcc/crt1.c: New file.
* lib/linux/arm-mes-gcc/mini.c: New file.
* lib/arm-mes-gcc/setjmp.c: New file.

Co-Authored-By: Danny Milosavljevic <dannym@scratchpost.org>
---
 lib/arm-mes-gcc/setjmp.c     | 61 +++++++++++++++++++++++++++++
 lib/linux/arm-mes-gcc/crt1.c | 76 ++++++++++++++++++++++++++++++++++++
 lib/linux/arm-mes-gcc/mini.c | 59 ++++++++++++++++++++++++++++
 3 files changed, 196 insertions(+)
 create mode 100644 lib/arm-mes-gcc/setjmp.c
 create mode 100644 lib/linux/arm-mes-gcc/crt1.c
 create mode 100644 lib/linux/arm-mes-gcc/mini.c

diff --git a/lib/arm-mes-gcc/setjmp.c b/lib/arm-mes-gcc/setjmp.c
new file mode 100644
index 00000000..c9e8b591
--- /dev/null
+++ b/lib/arm-mes-gcc/setjmp.c
@@ -0,0 +1,61 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <setjmp.h>
+#include <stdlib.h>
+
+void
+__attribute__ ((noinline))
+longjmp (jmp_buf env, int val)
+{
+  // *INDENT-OFF*
+  asm (
+       "mov r0, %0\n\t"
+       "mov r1, %1\n\t"
+       "cmp r1, #0\n\t"
+       "moveq r1, #1\n\t" /* returning 0 is not allowed, even when the user 
wanted to. */
+       "ldr r13, [r0], #4\n\t" /* stack pointer (sp) */
+       "ldr r14, [r0], #4\n\t" /* link register (lr) */
+       "ldmia r0!, {r4, r5, r6, r7, r8, r9, r10, r11}\n\t"
+       // TODO: If using VFP, vldmia r0!, {d8-d15}
+       "mov r0, r1\n\t"
+       :
+       : "r" (env), "r" (val));
+  // *INDENT-ON*
+  // not reached
+}
+
+int
+__attribute__ ((noinline))
+setjmp (jmp_buf env)
+{
+  // *INDENT-OFF*
+  asm (
+       "mov r0, %0\n\t"
+       "str r13, [r0], #4\n\t" /* stack pointer (sp) */
+       "str r14, [r0], #4\n\t" /* link register (lr) */
+       "stmia r0!, {r4, r5, r6, r7, r8, r9, r10, r11}\n\t"
+       // TODO: If using VFP, vstmia r0!, {d8-d15}
+       :
+       : "r" (env)
+       : "r0");
+  // *INDENT-ON*
+  return 0;
+}
diff --git a/lib/linux/arm-mes-gcc/crt1.c b/lib/linux/arm-mes-gcc/crt1.c
new file mode 100644
index 00000000..67e7ad29
--- /dev/null
+++ b/lib/linux/arm-mes-gcc/crt1.c
@@ -0,0 +1,76 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2017,2018,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <mes/lib-mini.h>
+//int main (int argc, char *argv[], char *envp[]);
+
+/* Note: GCC automatically emits a preable in order to set up the frame 
pointer:
+"push {fp}"
+"add fp, sp, 0"
+ */
+// *INDENT-OFF*
+void
+_start ()
+{
+  asm (
+       "mov    r0,#0\n\t"
+       "mov    %0,r0\n"
+       : "=r" (__stdin)
+       : //no inputs ""
+       );
+
+  asm (
+       "mov    r0,#1\n\t"
+       "mov    %0,r0\n"
+       : "=r" (__stdout)
+       : //no inputs ""
+       );
+
+  asm (
+       "mov    r0,#2\n\t"
+       "mov    %0,r0\n"
+       : "=r" (__stderr)
+       : //no inputs ""
+       );
+
+  /* environ = argv + argc + 1 */
+  asm (
+       "ldr     r0,[fp,#4]\n\t" /* r0 = argc */
+       "add     r1,fp,#8\n\t" /* r1 = &argv[0] */
+       "add     r2,r0,#1\n\t" /* r2 = r0 + 1 */
+       "lsl     r2,#2\n\t" /* r2 = (r0 + 1) << 2 */
+       "add     r2,r2,r1\n\t" /* r2 = ((r0 + 1) << 2) + r1 */
+       "push    {r2}\n\t" /* envp */
+       "push    {r1}\n\t" /* argv */
+       "push    {r0}\n\t" /* argc */
+       "mov     %0,r2\n\t"
+       : "=r" (environ)
+       : //no inputs ""
+       );
+  asm (
+       "ldr     r0,[sp]\n\t" /* argc */
+       "ldr     r1,[sp, #4]\n\t" /* argv */
+       "ldr     r2,[sp, #8]\n\t" /* envp */
+       "bl      main\n\t"
+       "mov    r7, #1\n\t"
+       "swi     #0\n\t"
+       "wfi     \n\t"
+       );
+}
diff --git a/lib/linux/arm-mes-gcc/mini.c b/lib/linux/arm-mes-gcc/mini.c
new file mode 100644
index 00000000..e524cc7e
--- /dev/null
+++ b/lib/linux/arm-mes-gcc/mini.c
@@ -0,0 +1,59 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2016,2017,2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "mes/lib-mini.h"
+
+#define SYS_exit   "0x01"
+#define SYS_write  "0x04"
+
+// *INDENT-OFF*
+void
+_exit (int code)
+{
+  asm (
+       "mov    r7, $"SYS_exit"\n\t"
+       "mov    r0, %0\n\t"
+       "swi    $0\n\t"
+       : // no outputs "=" (r)
+       : "r" (code)
+       : "r0", "r7"
+       );
+  // not reached
+  _exit (0);
+}
+
+ssize_t
+_write (int filedes, void const *buffer, size_t size)
+{
+  long r;
+  asm (
+       "mov    r7, $"SYS_write"\n\t"
+       "mov    r0, %1\n\t"
+       "mov    r1, %2\n\t"
+       "mov    r3, %3\n\t"
+       "swi    $0\n\t"
+       "mov    %0, r0\n\t"
+       : "=r" (r)
+       : "r" (filedes), "r" (buffer), "r" (size)
+       : "r0", "r1", "r2", "r7"
+       );
+  return r;
+}
+// *INDENT-ON*