From ca56c4f1cfd9fe27de2e2781e660953060f1fda0 Mon Sep 17 00:00:00 2001
From: Adam Greenwood-Byrne <adam@isometim.es>
Date: Sun, 14 Mar 2021 20:18:11 +0000
Subject: [PATCH] Add wwipe.c and examples/wgt24.c to exercise it

---
 part12-wgt/examples/wgt24.c | 141 ++++++++++++++++++++++++++++++++++++
 part12-wgt/wgt.h            |   1 +
 part12-wgt/wwipe.c          |  63 ++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 part12-wgt/examples/wgt24.c
 create mode 100644 part12-wgt/wwipe.c

diff --git a/part12-wgt/examples/wgt24.c b/part12-wgt/examples/wgt24.c
new file mode 100644
index 0000000..3dff3da
--- /dev/null
+++ b/part12-wgt/examples/wgt24.c
@@ -0,0 +1,141 @@
+#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 ########
+
+void wgt24()
+{
+  block screen1, screen2;
+  color pal[256];
+  int i;
+
+  set_clock_rate(get_max_clock());
+  mem_init();
+  vga256 ();
+
+  /* Note: This text will be on our second screen - used for wipes */
+  wtextcolor (vgapal[15]);                      /* Use index 15 for text */
+  wouttextxy (0, 0, NULL, "SCREEN BUFFER #2");
+  wouttextxy (0, 50, NULL, "This screen is one of our 2 screens");
+  wouttextxy (0, 58, NULL, "used to perform the wipe effect.");
+  wouttextxy (46, 100, NULL, "Press a key to perform wipe");
+  screen2 = wnewblock (0, 0, 319, 199); /* Allocate memory for screen2 */
+
+  extern unsigned char _binary_bin_wgt1_pal_start[];
+  wloadpalette (&_binary_bin_wgt1_pal_start[0], pal);
+  wsetpalette (0, 255, pal);
+  extern unsigned char _binary_bin_wgt2_blk_start[];
+  screen1 = wloadblock (&_binary_bin_wgt2_blk_start[0]);
+
+  getch();
+
+  for (i = 0; i < 200; i++)
+    {
+     wwipe (0, 0, 319, i, screen1);             /* Wipe screen down from right */
+     delay (1);
+     wwipe (319, 199,0, 199 - i, screen1);      /* Wipe screen up from left */
+     delay (1);
+    }
+  getch ();
+
+  /* Now wipe on the black screen using horizontal lines meeting at middle */
+  for (i = 0; i < 100; i++)
+    {
+     wwipe (0, i, 319, i, screen2);
+     delay (1);
+     wwipe (0, 199 - i, 319, 199 - i, screen2);
+     delay (1);
+    }
+
+  getch ();
+
+  /* Now perform a "circular" wipe, by going around the screen from center */
+  for (i = 0; i < 320; i++)
+    {
+     wwipe (159, 99, i, 0, screen1);
+     delay (1);
+    }
+
+  for (i = 0; i < 200; i++)
+    {
+     wwipe (159, 99, 319, i, screen1);
+     delay (1);
+    }
+
+  for (i = 319; i >= 0; i--)
+    {
+     wwipe (159, 99, i, 199, screen1);
+     delay (1);
+    }
+
+  for (i = 199; i >= 0; i--)
+    {
+     wwipe (159, 99, 0, i, screen1);
+     delay (1);
+    }
+  getch ();
+
+  /* Clear with black screen by wiping top to bottom */
+  for (i = 0; i < 200; i++)
+    {
+     wwipe (0, i, 319, i, screen2);
+     delay (1);
+    }
+  getch ();
+
+  wfreeblock (screen1); /* remember to free that memory */
+  wfreeblock (screen2);
+}
+
+void main()
+{
+    wgt24();
+    while (1);
+}
diff --git a/part12-wgt/wgt.h b/part12-wgt/wgt.h
index 82d6ba6..34fe294 100644
--- a/part12-wgt/wgt.h
+++ b/part12-wgt/wgt.h
@@ -116,3 +116,4 @@ void wdissolve (block sourceimage, short *pattern, short speed);
 void wsetscreen (block image);
 void wnormscreen (void);
 void wvertres (short x, short y, short y2, block image);
+void wwipe (short x, short y, short x2, short y2, block image);
diff --git a/part12-wgt/wwipe.c b/part12-wgt/wwipe.c
new file mode 100644
index 0000000..8e4495c
--- /dev/null
+++ b/part12-wgt/wwipe.c
@@ -0,0 +1,63 @@
+#include "wgt.h"
+
+void wwipe (short x, short y, short x2, short y2, block image)
+{
+  short t, distance;
+  short wx, wy, dx, dy, bdx, bdy, incx, incy;
+  unsigned int col;
+  short swidth;
+
+    swidth = wgetblockwidth (image);
+
+    /* Do the line formula */
+    dx = x2 - x;
+    dy = y2 - y;
+    t = 0; wx = 0; wy = 0;
+    if  (dy < 0) incy = - 1; else incy = 1;
+    if  (dx < 0) incx = - 1; else incx = 1;
+    bdx = abs (dx);
+    bdy = abs (dy);
+    if  (bdx > bdy) distance = bdx;
+    else distance = bdy;
+    if  (distance == bdx)
+    {
+      while  (t <= distance)
+      {
+	if  ((x >= tx) & (y >= ty) & (y <= by) & (x <= bx))
+	  /* inside clipping? */
+	{
+	  col = image[y * swidth + x + 2];
+	  /* get the colour */
+	  abuf[y * WGT_SYS.xres + x] = col;
+	  /* put the pixel */
+	}
+	wy += bdy;
+	x += incx;
+	t++;
+	if  (wy >= distance)
+	{
+	  wy -= distance;
+	  y += incy;
+	}
+      }
+    }
+    else
+    {
+      while  (t <= distance)
+      {
+	if  ((x >= tx) & (y >= ty) & (y <= by) & (x <= bx))
+	{
+	  col = image[y * swidth + x + 2];
+	  abuf[y*WGT_SYS.xres + x] = col;
+	}
+	wx += bdx;
+	if  (wx >= distance)
+	{
+	  wx -= distance;
+	  x += incx;
+	}
+	y += incy;
+	t++;
+      }
+    }
+}