Merge pull request boriel-basic#284 from boriel/chore/add_scrview_tool

Add a simple .SCR viewer

tools/scrview.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import sys
+import pygame
+from typing import List, Tuple
+
+
+WIDTH = 256   # ZX Spectrum screen width in pixels
+HEIGHT = 192  # ZX Spectrum screen height in pixels
+SCALE = 4     # Scale
+
+
+# Colors
+BLACK = 0
+BLUE = 1
+RED = 2
+MAGENTA = 3
+GREEN = 4
+CYAN = 5
+YELLOW = 6
+WHITE = 7
+
+BRIGHT_OFFSET = 20
+SCREEN_AREA_SIZE = 6144
+
+
+# PALETTE[<color>] will return the expected color. Add 0x28 to increase bright
+PALETTE = [
+    (0, 0, 0),
+    (0, 0, 0xD7),
+    (0xD7, 0, 0),
+    (0xD7, 0, 0xD7),
+    (0, 0xD7, 0),
+    (0, 0xD7, 0xD7),
+    (0xD7, 0xD7, 0),
+    (0xD7, 0xD7, 0xD7)
+]
+
+
+TABLE = None  # Table of bytes to tuple of binaries
+
+
+def to_bin(x: int):
+    result = []
+
+    for i in range(8):
+        result.insert(0, x & 1)
+        x >>= 1
+
+    return result
+
+
+def get_attr(data: List[int], offset) -> int:
+    """ For a given offset in the drawing region, return the attribute.
+    This is a bit tricky for the speccy as the screen memory is not linear
+    """
+    k = (offset >> 3) & 0x300
+    r = offset & 0xFF
+    return data[SCREEN_AREA_SIZE + k + r]
+
+
+def get_xy_coord(offset: int) -> Tuple[int, int]:
+    """ Given an offset, return the x, y coordinate
+    of that byte in the display """
+    x = (offset & 0x1F) << 3    # mod 32
+    y0 = (offset >> 5) & 0xC0   # offset / 2048
+    y1 = (offset >> 8) & 0x07   # offset / 256
+    y2 = (offset >> 2) & 0x38   # offset / 8
+    y = y0 + y1 + y2
+    return x * SCALE, y * SCALE
+
+
+def plot_byte(screen, data: List[int], offset: int):
+    """ Draws a pixel at the given X, Y coordinate
+    """
+    global TABLE
+
+    byte_ = TABLE[data[offset]]
+    attr = get_attr(data, offset)
+
+    ink_ = attr & 0x7
+    paper_ = (attr >> 3) & 0x7
+    bright = (attr >> 6) & 0x1
+
+    paper = tuple(x + bright for x in PALETTE[paper_])
+    ink = tuple(x + bright for x in PALETTE[ink_])
+    palette = [paper, ink]
+
+    x0, y0 = get_xy_coord(offset)
+
+    for x, bit_ in enumerate(byte_):
+        screen.fill(palette[bit_], pygame.Rect(x0 + x * SCALE, y0, SCALE, SCALE))
+
+
+def paint(data: List[int]):
+    pygame.init()
+    screen = pygame.display.set_mode([WIDTH * SCALE, HEIGHT * SCALE])
+
+    for i in range(SCREEN_AREA_SIZE):
+        plot_byte(screen, data, i)
+
+    pygame.display.flip()
+
+    # Wait for quit
+    running = True
+    while running:
+        for event in pygame.event.get():
+            if event.type == pygame.QUIT:
+                running = False
+
+    pygame.quit()
+
+
+if __name__ == '__main__':
+    # initialize Table
+    TABLE = [to_bin(x) for x in range(256)]
+
+    with open(sys.argv[1], 'rb') as f:
+        data = f.read()
+
+    paint(data)