From 74fe4fda2a3059b97d1bfcc03e37be1a19ea82fe Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Sat, 26 Jun 2021 18:19:14 +0000
Subject: Fast mode working and partial text mode.  Plan on attempting a ULA
 emulation.

---
 source/zx81.c | 161 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 158 insertions(+), 3 deletions(-)

(limited to 'source/zx81.c')

diff --git a/source/zx81.c b/source/zx81.c
index b2d85b1..1335d0b 100644
--- a/source/zx81.c
+++ b/source/zx81.c
@@ -29,6 +29,7 @@
 
 #include "zx81.h"
 #include "gui.h"
+#include "framebuffer.h"
 
 #include "stream.h"
 
@@ -655,10 +656,164 @@ void ZX81Init(Z80 *z80)
 }
 
 
-void ZX81RenderDisplay(Framebuffer *fb)
+void ZX81RenderDisplay(Framebuffer *fb, Z80 *z80)
 {
-    FB_Clear(fb, COL_BLACK);
-    FB_Centre(fb, "TODO", 10, COL_WHITE, COL_TRANSPARENT);
+    u16 black;
+    u16 white;
+
+    black = FB_GetColour(COL_BLACK);
+    white = FB_GetColour(COL_WHITE);
+
+    if (fast_mode)
+    {
+        u16 x;
+        u16 y;
+
+        for(x = 0; x < fb->width; x++)
+        {
+            for(y = 0; y < fb->height; y++)
+            {
+                FB_ADDR(fb, x, y) = ((x+y) % 2) ? black : white;
+            }
+        }
+    }
+    else if (hires)
+    {
+        int x;
+        int y;
+        Z80Byte *dfile;
+
+        FB_Clear(fb, COL_WHITE);
+
+        dfile = mem + WORD(DFILE);
+
+        dfile++;
+
+        for(y = 0; y < SCR_H; y++)
+        {
+            for(x = 0; x < TXT_W; x++)
+            {
+                int ch = *dfile++;
+                int px;
+                uint pen;
+                uint paper;
+                int data;
+
+                if (ch == 118)
+                {
+                    break;
+                }
+
+                if (ch & 0x80)
+                {
+                    pen = white;
+                    paper = black;
+                    ch -= 0x80;
+                }
+                else
+                {
+                    pen = black;
+                    paper = white;
+                }
+
+                data = mem[z80->I * 256 + ch * 8];
+
+                for(px = 0; px < 8; px++)
+                {
+                    if (data & 0x80)
+                    {
+                        FB_ADDR(fb,
+                                x * 8 + px + 72,
+                                fb->height - 24 - y) = pen;
+                    }
+                    else
+                    {
+                        FB_ADDR(fb,
+                                x * 8 + px + 72,
+                                fb->height - 24 - y) = paper;
+                    }
+
+                    data = data<<1;
+                }
+            }
+
+            if (*dfile == 118)
+            {
+                dfile++;
+            }
+        }
+    }
+    else
+    {
+        int x;
+        int y;
+        Z80Byte *dfile;
+
+        FB_Clear(fb, COL_WHITE);
+
+        dfile = mem + WORD(DFILE);
+
+        dfile++;
+
+        for(y = 0; y < TXT_H; y++)
+        {
+            for(x = 0; x < TXT_W; x++)
+            {
+                int ch = *dfile++;
+                int px;
+                int py;
+                uint pen;
+                uint paper;
+
+                if (ch == 118)
+                {
+                    break;
+                }
+
+                if (ch & 0x80)
+                {
+                    pen = white;
+                    paper = black;
+                    ch -= 0x80;
+                }
+                else
+                {
+                    pen = black;
+                    paper = white;
+                }
+
+                for(py = 0; py < 8; py++)
+                {
+                    int data;
+
+                    data = mem[z80->I * 256 + ch * 8 + py];
+
+                    for(px = 0; px < 8; px++)
+                    {
+                        if (data & 0x80)
+                        {
+                            FB_ADDR(fb,
+                                    x * 8 + px + 72,
+                                    fb->height - 24 - y * 8 - py) = pen;
+                        }
+                        else
+                        {
+                            FB_ADDR(fb,
+                                    x * 8 + px + 72,
+                                    fb->height - 24 - y * 8 - py) = paper;
+                        }
+
+                        data = data<<1;
+                    }
+                }
+            }
+
+            if (*dfile == 118)
+            {
+                dfile++;
+            }
+        }
+    }
 }
 
 
-- 
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