Import official C23 code examples for Modern C (Jens Gustedt, 2024)HEADupstream-importmain

- Add official C source files, Makefile, c23-fallback.h, and LICENSE
- Update README.md with study mirror notice

1 files changed, 57 insertions, 0 deletions

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+/**
+ ** @brief A toy example for a usage of the #embed directive.
+ **
+ ** We just embed the source of this program into the executable and
+ ** print it.
+ **
+ ** If the #embed directive is entirely supported, the preprocessor
+ ** should do macro expansion of `__FILE__`. If the directory of the
+ ** source file is in the include path for embed.c, the source should
+ ** just be included like that.
+ **
+ ** If the directive is not supported you could try to compile this
+ ** anyhow by using https://sentido-labs.com/en/library/cedro/. Cedro
+ ** does not allow to do macro expansion for the argument of the
+ ** directive, so we have to give this explicitly.
+ **
+ ** For the example itself to output properly, the source and
+ ** execution encoding should not be too different.
+ **/
+
+#include "c23-fallback.h"
+#include <stdio.h>
+#include <string.h>
+
+// define a character array that will contain the entire
+// source file
+static char const here[] = {
+
+// Cedro does not work with blanks between the # and any directive
+#pragma Cedro 1.0 embed
+#embed "embed.c"
+
+};
+
+// define another character array that has the same size
+static char there[sizeof here];
+
+int main(int argc, char* argv[static argc+1]) {
+  size_t ibytes = 0;
+  int cmp = 1000;
+  // Open the file in binary mode.
+  FILE* inp = fopen(__FILE__, "rb");
+  if (inp) {
+    // read the file as binary
+    ibytes = fread(there, 1, sizeof there, inp);
+    cmp = memcmp(here, there, sizeof here);
+    fclose(inp);
+  } else {
+    printf("could not open %s\n", __FILE__);
+    printf("+++++++++++++++++++++++++++++++++++++++++++++++\n");
+  }
+  size_t obytes = fwrite(here, 1, sizeof here, stdout);
+  printf("+++++++++++++++++++++++++++++++++++++++++++++++\n");
+  printf("in %zu, out %zu, bytes are %s\n",
+         ibytes, obytes,
+         cmp < 0 ? "smaller" : (cmp > 0 ? "greater" : "equal"));
+}