LCD emulation

h8536/emulator/peripherals/lcd.py

@@ -1,5 +1,69 @@
 from __future__ import annotations
 
+from dataclasses import dataclass, field
+
 
 LCD_E_CLOCK_STATUS = 0xF200
 LCD_E_CLOCK_DATA = 0xF201
+
+LCD_LINE_WIDTH = 16
+LCD_LINE_STARTS = (0x00, 0x40, 0x10, 0x50)
+LCD_DDRAM_SIZE = 0x80
+
+
+@dataclass
+class LCD:
+    ddram: bytearray = field(default_factory=lambda: bytearray([0x20] * LCD_DDRAM_SIZE))
+    cursor: int = 0
+    data_latch: int = 0
+    command_latch: int = 0
+
+    def read_status(self) -> int:
+        return self.cursor & 0x7F
+
+    def read_data(self) -> int:
+        return self.data_latch & 0xFF
+
+    def write_command(self, value: int) -> None:
+        value &= 0xFF
+        self.command_latch = value
+        if value & 0x80:
+            self.cursor = value & 0x7F
+        elif value == 0x01:
+            self.ddram[:] = bytes([0x20]) * LCD_DDRAM_SIZE
+            self.cursor = 0
+        elif value == 0x02:
+            self.cursor = 0
+
+    def write_data(self, value: int) -> None:
+        value &= 0xFF
+        self.data_latch = value
+        if 0 <= self.cursor < LCD_DDRAM_SIZE:
+            self.ddram[self.cursor] = value
+        self.cursor = (self.cursor + 1) & 0x7F
+
+    def line_text(self, line: int, width: int = LCD_LINE_WIDTH) -> str:
+        if not 0 <= line < len(LCD_LINE_STARTS):
+            raise ValueError(f"LCD line out of range: {line}")
+        start = LCD_LINE_STARTS[line]
+        return "".join(_display_char(self.ddram[(start + offset) & 0x7F]) for offset in range(width))
+
+    def display_lines(self, lines: int = 4, width: int = LCD_LINE_WIDTH) -> list[str]:
+        return [self.line_text(line, width) for line in range(lines)]
+
+    def display_text(self, lines: int = 4, width: int = LCD_LINE_WIDTH) -> str:
+        return " | ".join(self.display_lines(lines, width))
+
+
+def _display_char(value: int) -> str:
+    return chr(value) if 0x20 <= value <= 0x7E else "."
+
+
+__all__ = [
+    "LCD",
+    "LCD_DDRAM_SIZE",
+    "LCD_E_CLOCK_DATA",
+    "LCD_E_CLOCK_STATUS",
+    "LCD_LINE_STARTS",
+    "LCD_LINE_WIDTH",
+]