add wait_end_of_frame and its demo

demo/demo.c

@@ -6,6 +6,7 @@
 #include "demo_interrupt.h"
 #include "demo_extvid.h"
 #include "demo_blank.h"
+#include "demo_end_of_frame.h"
 
 void help() {
    woz_puts(
@@ -16,6 +17,7 @@ void help() {
       "A AMIGA HAND\r"
       "I INTERRUPT\r"
       "E FLIP EXT VIDEO\r"
+      "F TEST END-OF-FRAME\r"
       "B BLANK ON/OFF\r"
       "H HELP\r"
       "0 EXITS\r\r"
@@ -35,6 +37,7 @@ void main() {
       else if(key == 'A')  demo_amiga_hand();
       else if(key == 'I')  demo_interrupt();
       else if(key == 'E')  flip_external_input();
+      else if(key == 'F')  demo_end_of_frame();
       else if(key == 'B')  flip_blank();
       else if(key == 'H')  help();
       else if(key == '0')  break;

demo/demo_end_of_frame.h

@@ -0,0 +1,26 @@
+void demo_end_of_frame() {
+   tms_init_regs(SCREEN1_TABLE);
+   screen1_prepare();
+   screen1_load_font();
+
+   screen1_puts(
+      CLS "\n"
+      "Waitining for 600 ticks by\n"
+      "counting the " REVERSE_ON "END-OF-FRAME" REVERSE_OFF " bit.\n\n"
+      "It will take about 10 seconds.\n\n"
+   );
+
+   word secs = 0;
+   word ticks = 0;
+   while(secs<10) {
+      tms_wait_end_of_frame();
+      ticks++;
+      if(ticks==60) {
+         secs++;
+         ticks = 0;
+         screen1_puts("60 ticks!\n");
+      }
+   }
+   screen1_puts("\n\nDONE!");
+}
+

lib/tms9918.h

@@ -8,6 +8,7 @@
 // TODO finalize hexdump.js and update README.md
 // TODO allow redefinition of I/O ports
 // TODO wait_end_of_frame() 
+// TODO screen1() and screen2() helpers
 
 #pragma encoding(ascii)    // encode strings in plain ascii
 
@@ -157,7 +158,7 @@ void tms_set_external_video(byte val) {
    tms_write_reg(0, regvalue);
 }
 
-void tms_wait_end_of_frame() {
+inline void tms_wait_end_of_frame() {
    while(!FRAME_BIT(TMS_READ_CTRL_PORT));
 }