From 239a0690e1e5a5e00b02019f75f7afc283275b99 Mon Sep 17 00:00:00 2001
From: Adam Greenwood-Byrne <adam@isometim.es>
Date: Fri, 19 Mar 2021 19:59:27 +0000
Subject: [PATCH] Added wbezier.c, wspoly.c - exercised by examples/wgt33.c,
 fixed memory alignment issue with lib/mem.c

---
 part12-wgt/examples/wgt33.c |  99 +++++++++++++++++++++++++++++++++++
 part12-wgt/lib/mem.c        |   7 ++-
 part12-wgt/wbezier.c        |  59 +++++++++++++++++++++
 part12-wgt/wgt.h            |  16 ++++++
 part12-wgt/winitply.c       |  41 +++++++++++++++
 part12-wgt/wspoly.c         | 100 ++++++++++++++++++++++++++++++++++++
 6 files changed, 320 insertions(+), 2 deletions(-)
 create mode 100644 part12-wgt/examples/wgt33.c
 create mode 100644 part12-wgt/wbezier.c
 create mode 100644 part12-wgt/winitply.c
 create mode 100644 part12-wgt/wspoly.c

diff --git a/part12-wgt/examples/wgt33.c b/part12-wgt/examples/wgt33.c
new file mode 100644
index 0000000..3c1b6c0
--- /dev/null
+++ b/part12-wgt/examples/wgt33.c
@@ -0,0 +1,99 @@
+#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 ########
+
+#define NUM_IN 5       /* number of random points */
+#define NUM_OUT 30     /* number of points of bezier curve */
+/* Fewer points will make more chunky line */
+
+void wgt33()
+{
+  tpolypoint inpoint[NUM_IN];   /* Array with the normal curve points */
+  tpolypoint outpoint[NUM_OUT]; /* Array with smooth curve points */
+  block other;                  /* Pointer to our second screen */
+  int i;			/* Loop counter */
+
+  set_clock_rate(get_max_clock());
+  mem_init();
+  vga256 ();			/* Initialize graphics mode */
+
+  other = wnewblock (0, 0, 319, 199);	/* Allocate second screen */
+
+  wsetcolor (vgapal[15]);	/* Draw with white */
+
+  do {
+    wsetscreen (other);		/* We'll draw on the hidden screen */
+    wcls (vgapal[0]);		/* Clear it with black */
+
+    for (i = 0; i < NUM_IN; i++)  /* Randomize the BEZIER control pts */
+      {
+       inpoint[i].x = rand() % 320;
+       inpoint[i].y = rand() % 200;
+      }
+
+    wbezier (inpoint, NUM_IN, outpoint, NUM_OUT);	/* Generate line */
+
+    whollowpoly (outpoint, NUM_OUT, 0, 0, OPEN_POLY);
+      /* draw the smooth curve */
+
+    wnormscreen ();		/* Reset drawing to visual screen */
+    wputblock (0, 0, other, 0);	/* Show the screen */
+    getch();
+  } while (1);
+
+  wfreeblock (other);		/* Free our screen buffer */
+}
+
+void main()
+{
+    wgt33();
+    while (1);
+}
diff --git a/part12-wgt/lib/mem.c b/part12-wgt/lib/mem.c
index e466404..18e1839 100644
--- a/part12-wgt/lib/mem.c
+++ b/part12-wgt/lib/mem.c
@@ -16,8 +16,8 @@ void mem_init()
 {
    // Align the start of heap to an 8-byte boundary
 
-   if ((long)&HEAP_START % 8 != 0) {
-      HEAP_START += 8 - ((long)&HEAP_START % 8);
+   if ((long)HEAP_START % 8 != 0) {
+      HEAP_START += 8 - ((long)HEAP_START % 8);
    }
    HEAP_END = (unsigned char *)(HEAP_START + HEAP_SIZE);
 
@@ -28,6 +28,9 @@ void *malloc(unsigned int size)
 {
    if (size > 0) {
       void *allocated = freeptr;
+      if ((long)allocated % 8 != 0) {
+         allocated += 8 - ((long)allocated % 8);
+      }
     
       if ((unsigned char *)(allocated + size) > HEAP_END) {
          return 0;
diff --git a/part12-wgt/wbezier.c b/part12-wgt/wbezier.c
new file mode 100644
index 0000000..79d6b39
--- /dev/null
+++ b/part12-wgt/wbezier.c
@@ -0,0 +1,59 @@
+#include "wgt.h"
+#include "include/mem.h"
+
+void wbezier (tpolypoint *rawpts, short numraw, tpolypoint *curvepts, short numcurve)
+/* Bezier curve algorithm submitted to us by Claude Morais */
+{
+  double *combi;
+  double deltat, temp;
+  double prod,quot;
+  double sumx,sumy;
+  short  tmp, count;
+  
+  combi = malloc (sizeof(double)*numraw);
+
+  numraw--;
+  deltat = 1.0 / (numcurve - 1);
+  combi[0] = combi[numraw] = 1.0;
+
+  for  (tmp = 0; tmp <= (numraw - 2); tmp++)
+    combi[tmp + 1] = (combi[tmp] * (numraw - tmp)) / (tmp + 1);
+  
+  for  (count = 0; count < numcurve; count++)
+    {
+     if ((temp = count*deltat) <= 0.5)
+       {
+	quot = prod = 1.0 - temp;
+	for  (tmp = 1; tmp < numraw; tmp++)
+	  prod *= quot;
+
+	quot = temp / quot;
+	sumx = rawpts[numraw].x;
+	sumy = rawpts[numraw].y;
+	for  (tmp = numraw - 1; tmp >= 0; tmp--)
+	  {
+	   sumx = combi[tmp]* rawpts[tmp].x + quot* sumx;
+	   sumy = combi[tmp]* rawpts[tmp].y + quot* sumy;
+	  }
+       }
+     else
+       {
+	quot = prod = temp;
+	for (tmp = 1; tmp < numraw; tmp++)
+	  prod *= quot;
+
+	quot = (1.0 - temp) / quot;
+	sumx = rawpts[0].x;
+	sumy = rawpts[0].y;
+	for (tmp = 1; tmp <= numraw; tmp++)
+	  {
+	   sumx = combi[tmp]* rawpts[tmp].x + quot* sumx;
+	   sumy = combi[tmp]* rawpts[tmp].y + quot* sumy;
+	  }
+       }
+     curvepts[count].x = (sumx*prod);
+     curvepts[count].y = (sumy*prod);
+    }
+  
+  free (combi);
+}
diff --git a/part12-wgt/wgt.h b/part12-wgt/wgt.h
index 59041d1..f6d5a3b 100644
--- a/part12-wgt/wgt.h
+++ b/part12-wgt/wgt.h
@@ -51,6 +51,19 @@ extern unsigned int currentcolor;
 /* Clipping boundaries */
 extern short bx,by,tx,ty;
 
+/* Polygon point definition */
+typedef struct
+{
+  short x,y;   /* Coordinate on the screen */
+  short sx,sy; /* Coordinate on the texture if texture is used,
+                  otherwise sx = color point */
+               /* sx is used for Gouraud shading as well (color of the point) */
+} tpolypoint;
+
+/* whollowpoly types */
+#define CLOSED_POLY 0
+#define OPEN_POLY 1
+
 // ######## HELPER FUNCTIONS ########
 
 void *memset(void *dest, unsigned int val, unsigned len);
@@ -126,3 +139,6 @@ void wcopyscreen (short x, short y, short x2, short y2, block source, short dest
 void wsline (short x, short y, short x2, short y2, short *y_array);
 void wwarp (short sx, short ex, short *tpy, short *bty, block ptr, short mode);
 void wresize_column (short x, short y, short y2, block image, short column, short mode);
+void wsolidpoly (tpolypoint *vertexlist, short numvertex, short x, short y, void (*customline)(short, short, short));
+void whollowpoly(tpolypoint *vertexlist, short numvertex, short x, short y, short closemode);
+void wbezier (tpolypoint *rawpts, short numraw, tpolypoint *curvepts, short numcurve);
diff --git a/part12-wgt/winitply.c b/part12-wgt/winitply.c
new file mode 100644
index 0000000..24cde77
--- /dev/null
+++ b/part12-wgt/winitply.c
@@ -0,0 +1,41 @@
+#include "wgt.h"
+#include "include/mem.h"
+
+short *pinit_array;
+short *pstartx;
+short *pendx;
+short *pinten1;
+short *pinten2;
+short *polyx2;
+short *polyy2;
+short polygon_buffer_size;
+
+void winitpoly (short maxrows)
+{
+  int bytes;
+  int ctr;
+
+  polygon_buffer_size = maxrows;
+
+  bytes = 2 * maxrows;
+  pstartx = malloc (bytes);
+  pendx = malloc (bytes);
+  pinten1 = malloc (bytes);
+  pinten2 = malloc (bytes);
+  polyx2 = malloc (bytes);
+  polyy2 = malloc (bytes);
+  pinit_array = malloc (bytes);
+  for (ctr = 0; ctr < maxrows; ctr++)
+    pinit_array[ctr] = -16000;
+}
+
+void wdeinitpoly (void)
+{
+  free (pstartx);
+  free (pendx);
+  free (pinten1);
+  free (pinten2);
+  free (polyx2);
+  free (polyy2);
+  free (pinit_array);
+}
diff --git a/part12-wgt/wspoly.c b/part12-wgt/wspoly.c
new file mode 100644
index 0000000..8f60307
--- /dev/null
+++ b/part12-wgt/wspoly.c
@@ -0,0 +1,100 @@
+#include "wgt.h"
+
+extern short *pinit_array;
+extern short *pstartx;
+extern short *pendx;
+extern short polygon_buffer_size;
+
+static void wspolyline (short x1, short y1, short x2, short y2)
+{
+short tmx, tmy, y;
+long x, m;
+
+ if (y2 != y1)
+   {
+    if (y2 < y1)
+      {
+       tmy = y1;
+       y1 = y2;
+       y2 = tmy;
+       tmx = x1;
+       x1 = x2;
+       x2 = tmx;
+      }
+
+    x = (long)x1 << 8;
+    m = ((long)(x2 - x1) << 8) / ((long)(y2 - y1));
+    x++;
+    y1++;
+
+    for (y = y1; y <= y2; y++)
+      {
+       if ((y >= 0) && (y < WGT_SYS.yres)) {
+	 if (pstartx[y] == -16000) {
+	   pstartx[y] = x >> 8;
+	 } else {
+	   pendx[y] = x >> 8;
+         }
+       }
+       x += m;
+      }
+   }
+}
+
+void wsolidpoly (tpolypoint *vertexlist, short numvertex, short x, short y, void (*customline)(short, short, short))
+{
+short i;
+tpolypoint *curpt, *nextpt;
+
+  if (customline == NULL)
+    customline = whline;
+
+  curpt = vertexlist;
+  nextpt = vertexlist + 1;
+
+  memcpy (pstartx, pinit_array, polygon_buffer_size << 1);
+  memcpy (pendx, pinit_array, polygon_buffer_size << 1);
+
+  for (i = 0; i < numvertex - 1; i++)
+    {
+     wspolyline (curpt->x + x, curpt->y + y, nextpt->x + x, nextpt->y + y);
+     curpt++;
+     nextpt++;
+    }
+
+  nextpt = vertexlist;
+  wspolyline (curpt->x + x, curpt->y + y, nextpt->x + x, nextpt->y + y);
+
+  for (i = 0; i < WGT_SYS.yres; i++)
+    {
+     if (pstartx[i] != -16000)
+       {
+	if (pendx[i] == -16000)
+	  pendx[i] = pstartx[i];
+	(*customline)(pstartx[i], pendx[i], i);
+    }
+  }
+}
+
+
+void whollowpoly(tpolypoint *vertexlist, short numvertex, short x, short y, short closemode)
+{
+short i;
+tpolypoint *curpt, *nextpt;
+
+  curpt = vertexlist;
+  nextpt = vertexlist + 1;
+
+  for (i = 0; i < numvertex - 1; i++)
+    {
+     wline (curpt->x + x, curpt->y + y, nextpt->x + x, nextpt->y + y);
+     curpt++;
+     nextpt++;
+    }
+
+  if (closemode == CLOSED_POLY)
+    {
+     nextpt = vertexlist;
+     wline (curpt->x + x, curpt->y + y, nextpt->x + x, nextpt->y + y);
+    }
+}