add SIGINFO / SIGUSR1 signal to headless driver.

On *BSD and MacOS X, typing ^T in the terminal sends a SIGINFO which will dump the text screen to stdout.
On Linux (as well as *BSD, etc) `kill -SIGUSR1 pid` will do the same.

src/headless_driver.c

@@ -8,9 +8,129 @@
 #include "defc.h"
 #include "glog.h"
 
+#include <signal.h>
+
+
+extern int get_byte_at_address(int addr);
+
+static unsigned char fix_char(unsigned char c) {
+  // inverse upper case
+  if (c >= 0x00 && c <= 0x1f) return c + 0x40;
+
+  // inverse special
+  if (c >= 0x20 && c <= 0x3f) return c;
+
+  // mouse text
+  if (c >= 0x40 && c <= 0x5f) return ' ';
+
+  // inverse lowercase
+  if (c >= 0x60 && c <= 0x7f) return c;
+
+  // uppercase normal
+  if (c >= 0x80 && c <= 0x9f) return c - 0x40;
+  
+
+  // special characters, uppercase normal, lowercase normal.
+  if (c >= 0xa0 && c <= 0xff) return c - 0x80;
+
+  return ' ';
+}
+
+
+static void siginfo_handler(int signum) {
+
+  static unsigned table[] = {
+    0x0400,
+    0x0480,
+    0x0500,
+    0x0580,
+    0x0600,
+    0x0680,
+    0x0700,
+    0x0780,
+    0x0428,
+    0x04A8,
+    0x0528,
+    0x05A8,
+    0x0628,
+    0x06A8,
+    0x0728,
+    0x07A8,
+    0x0450,
+    0x04D0,
+    0x0550,
+    0x05D0,
+    0x0650,
+    0x06D0,
+    0x0750,
+    0x07D0,
+  };
+
+  extern int g_cur_a2_stat;
+  extern int get_byte_at_address(int addr);
+
+
+  if (g_cur_a2_stat & ALL_STAT_SUPER_HIRES) return; // not text...
+
+  int st80 = g_cur_a2_stat & ALL_STAT_VID80 /* ALL_STAT_ST80 */;
+
+  //if (!(g_cur_a2_stat & ALL_STAT_TEXT)) return; // text is not enabled.
+
+  char buffer[80+1];
+
+  for (int row = 0; row < 24; ++row) {
+    unsigned address = table[row];
+    int column = 0;
+
+    memset(buffer, ' ', sizeof(buffer));
+
+    for(int j = 0; j < 40; ++j, ++address) {
+
+      unsigned char c;
+
+      if (st80) {
+        c  = get_byte_at_address(0xe10000 + address);
+        c = fix_char(c);
+        buffer[column++] = c;
+      }
+
+      c  = get_byte_at_address(0xe00000 + address);
+      c = fix_char(c);
+      buffer[column++] = c;
+
+    }
+    if (st80) {
+      buffer[80] = '\n';
+      write(1, buffer, 81);
+    } else {
+      buffer[40] = '\n';
+      write(1, buffer, 41);
+    }
+  }
+  write(1, "\n\n", 2);
+}
+
 int
 main(int argc, char **argv)
 {
+
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+
+  sa.sa_flags = SA_RESTART;
+  sa.sa_handler = siginfo_handler;
+
+	#if defined(SIGINFO)
+	/* control-T by default */
+
+  sigaction(SIGINFO, &sa, NULL);
+  //signal(SIGINFO, siginfo_handler);
+  #endif
+
+	//signal(SIGUSR1, siginfo_handler);
+  sigaction(SIGUSR1, &sa, NULL);
+
+
 	return gsplusmain(argc, argv);
 }