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, 97 insertions, 0 deletions

diff --git a/termin.c b/termin.c
new file mode 100644
index 0000000..5de89da
--- /dev/null
+++ b/termin.c
@@ -0,0 +1,97 @@
+#include "termin.h"
+#include "c23-fallback.h"
+#include <termios.h>
+#include <stdio.h>
+#include <stdbool.h>
+#ifndef __STDC_NO_THREADS__
+# include <threads.h>
+#endif
+#include <ctype.h>
+#include <string.h>
+
+/* Store the flags as they were set before termin_unbuffered. */
+static tcflag_t termin_echo;
+
+/* The flags that we manipulate. */
+#define TERMIN_FLAGS (ECHO | ECHONL | ICANON)
+
+void termin_reset(void) {
+  struct termios term;
+  tcgetattr(0, &term);
+  term.c_lflag |= termin_echo;
+  tcsetattr(0, TCSAFLUSH, &term);
+}
+
+void termin_unbuffered(void) {
+  // have stdin unbuffered on stdio level
+  setvbuf(stdin, 0, _IONBF, 0);
+  // store the terminal settings with respect to the flags
+  struct termios term;
+  tcgetattr(0, &term);
+  termin_echo = term.c_lflag & TERMIN_FLAGS;
+  // install exit handlers
+  atexit(termin_reset);
+  at_quick_exit(termin_reset);
+  // change the terminal settings to raw mode
+  term.c_lflag &= ~TERMIN_FLAGS;
+  tcsetattr(0, TCSAFLUSH, &term);
+}
+
+static unsigned minc = 0;
+static unsigned maxc = UCHAR_MAX;
+
+static
+void term_init(void) {
+  while (!termin_trans[minc]) ++minc;
+  while (!termin_trans[maxc]) --maxc;
+}
+
+#ifndef __STDC_NO_THREADS__
+static once_flag term_once = ONCE_FLAG_INIT;
+#endif
+
+static
+bool termin_read_csi(size_t len, char command[len]) {
+  for (char *p = command, *stop = command+len-1; p < stop; ++p) {
+    int c = getchar();
+    // catch all: EOF, 0, control characters
+    if (c < ' ') return false;
+    p[0] = c;
+    if ('@' <= c && c <= '~') {
+      p[1] = 0;
+      return true;
+    }
+  }
+  return false;
+}
+
+char const* termin_read_esc(size_t len, char command[len]) {
+  command[1] = getchar();
+  switch (command[1]) {
+  case '[':
+    return
+      termin_read_csi(len-2, command+2)
+      ? command
+      : 0;
+  case 'N':
+  case 'O':
+  case 'Z':
+  case '%':
+    command[2] = getchar();
+    command[3] = 0;
+    return command;
+  default:
+    ungetc(command[1], stdin);
+    return nullptr;
+  }
+}
+
+char termin_translate(char const* command) {
+  call_once(&term_once, term_init);
+  for (unsigned c = minc; c <= maxc; ++c) {
+    if (termin_trans[c] && !strcmp(command, termin_trans[c])) {
+      return c;
+    }
+  }
+  return 0;
+}