wutnewlib: implement abort, assert and assert_func (#337)

* wutnewlib: implement abort, assert and assert_func

* wut_newlib: Trigger trap instruction on assert/abort

* wut_newlib: Replace snprintf with cafe-os equivalent.

libraries/wutnewlib/wut_newlib.c

@@ -1,9 +1,77 @@
 #include "wut_newlib.h"
 #include <coreinit/exit.h>
+#include <coreinit/debug.h>
+#include <coreinit/internal.h>
+#include <stdio.h>
+#include <string.h>
 
 void(*__wut_exit)(int rc);
 extern void __fini_wut(void);
 
+void __attribute__((weak))
+abort(void) {
+   const char *error_text = "Abort called.\n";
+   if (OSIsDebuggerPresent()) {
+      __asm__ __volatile__("mr 3, %0\n"      // load 'tmp' into r3
+                           "tw 0x1f, 31, 31" // DBGSTR_INSTRUCTION
+              :
+              : "r"(error_text)
+              : "r3");
+   }
+   OSFatal(error_text);
+   /* NOTREACHED */
+   while (1);
+}
+
+void __attribute__((weak))
+__assert_func(const char *file,
+              int line,
+              const char *func,
+              const char *failedexpr)
+{
+   char tmp[512] = {};
+   char buffer[512] = {};
+
+   __os_snprintf(tmp, sizeof(tmp), "assertion \"%s\" failed:\n file \"%s\", line %d%s%s",
+                 failedexpr, file, line,
+                 func ? ", function: " : "", func ? func : "");
+
+   // make sure to add a \n every 64 characters to fit on the DRC screen.
+   char *target_ptr = buffer;
+   int i = 0, j = 0, lineLength = 0;
+   while (tmp[i] != '\0' && j < sizeof(buffer) - 2) {
+      if (tmp[i] == '\n') {
+         lineLength = 0;
+      } else if (lineLength >= 64) {
+         target_ptr[j++] = '\n';
+         lineLength = 0;
+      }
+      target_ptr[j++] = tmp[i++];
+      lineLength++;
+   }
+
+   if (OSIsDebuggerPresent()) {
+      __asm__ __volatile__("mr 3, %0\n"      // load 'tmp' into r3
+                           "tw 0x1f, 31, 31" // DBGSTR_INSTRUCTION
+              :
+              : "r"(tmp)
+              : "r3");
+   }
+
+   OSFatal(buffer);
+   /* NOTREACHED */
+   while (1);
+}
+
+void __attribute__((weak))
+__assert(const char *file,
+         int line,
+         const char *failedexpr)
+{
+   __assert_func(file, line, NULL, failedexpr);
+   /* NOTREACHED */
+}
+
 void *_sbrk_r(struct _reent *ptr, ptrdiff_t incr) {
 	return __wut_sbrk_r(ptr, incr);
 }