From c6033ac35607bf9726af994e48a8077c21178306 Mon Sep 17 00:00:00 2001
From: Adam Greenwood-Byrne <adam@isometim.es>
Date: Fri, 19 Mar 2021 20:11:03 +0000
Subject: [PATCH] Added examples/wgt46.c to exercise whline()

---
 part12-wgt/examples/wgt46.c | 90 +++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 part12-wgt/examples/wgt46.c

diff --git a/part12-wgt/examples/wgt46.c b/part12-wgt/examples/wgt46.c
new file mode 100644
index 0000000..cb48c86
--- /dev/null
+++ b/part12-wgt/examples/wgt46.c
@@ -0,0 +1,90 @@
+#include "wgt.h"
+#include "include/mem.h"
+
+// ######## REQUIRED FUNCTIONS ########
+
+unsigned long state0 = 1000;
+unsigned long state1 = 2000;
+
+unsigned long rand(void)
+{
+    unsigned long s1 = state0;
+    unsigned long s0 = state1;
+
+    state0 = s0;
+    s1 ^= s1 << 23;
+    s1 ^= s1 >> 17;
+    s1 ^= s0;
+    s1 ^= s0 >> 26;
+    state1 = s1;
+
+    return state0 + state1;
+}
+
+void wait_msec(unsigned int n)
+{
+    register unsigned long f, t, r;
+
+    // Get the current counter frequency
+    asm volatile ("mrs %0, cntfrq_el0" : "=r"(f));
+    // Read the current counter
+    asm volatile ("mrs %0, cntpct_el0" : "=r"(t));
+    // Calculate expire value for counter
+    t+=((f/1000)*n)/1000;
+    do{asm volatile ("mrs %0, cntpct_el0" : "=r"(r));}while(r<t);
+}
+
+// ######## STUB FUNCTIONS ########
+
+unsigned int kb = 0;
+
+unsigned int kbhit(void) {
+    kb++;
+    return kb / 500;
+}
+
+void getch(void) {
+    wait_msec(0x500000);
+    kb = 0;
+}
+
+// ######## WGT EXAMPLES ########
+
+int loopctr;
+
+void timerctr(void)
+{
+  loopctr++;
+}
+
+void wgt46()
+{
+  short row;
+
+  set_clock_rate(get_max_clock());
+  mem_init();
+  vga256 ();                    /* Initializes WGT system       */
+  wcls (vgapal[0]);             /* Clear screen with color 0    */
+
+  row = 0;                      /* Start drawing at top row of screen */
+  loopctr = 0;
+  winittimer ();
+  wstarttimer (timerctr, 100);  /* Set timer to 100th of a second accuracy */
+  do {
+    wsetcolor (vgapal[rand () % 256]);  /* Pick a random color */
+    whline (0, 319, row++);     /* Draw the line */
+    if (row > 199)              /* Loop at end of screen */
+      row = 0;
+  } while (loopctr < 500);       
+
+  /* As soon as we reach 500 hundredths of a second (5 secs), end the routine
+     and reset the video mode */
+  wstoptimer ();
+  wdonetimer ();
+}
+
+void main()
+{
+    wgt46();
+    while (1);
+}