No Slot Clock

js/cards/nsc.js

@@ -0,0 +1,119 @@
+/* Copyright 2010-2019 Will Scullin <scullin@scullinsteel.com>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or
+ * implied warranty.
+ */
+
+import { debug } from '../util';
+
+export default function NoSlotClock(rom)
+{
+    var PATTERN = [
+        0xC5, 0x3A, 0xA3, 0x5C, 0xC5, 0x3A, 0xA3, 0x5C
+    ];
+    var A0 = 0x01;
+    var A2 = 0x04;
+
+    function _init() {
+        debug('NoSlotClock');
+    }
+
+    var _bits = [];
+    var _pattern = new Array(64);
+    var _patternIdx = 0;
+
+    function _patternMatch() {
+        for (var idx = 0; idx < 8; idx++) {
+            var byte = 0;
+            for (var jdx = 0; jdx < 8; jdx++) {
+                byte >>= 1;
+                byte |= _pattern.shift() ? 0x80 : 0x00;
+            }
+            if (byte !== PATTERN[idx]) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    function _calcBits() {
+        function shift(val) {
+            for (var idx = 0; idx < 4; idx++) {
+                _bits.push(val & 0x08 ? 0x01 : 0x00);
+                val <<= 1;
+            }
+        }
+        function shiftBCD(val) {
+            shift(parseInt(val / 10, 10));
+            shift(parseInt(val % 10, 10));
+        }
+
+        var now = new Date();
+        var year = now.getFullYear() % 100;
+        var day = now.getDate();
+        var weekday = now.getDay() + 1;
+        var month = now.getMonth() + 1;
+        var hour = now.getHours();
+        var minutes = now.getMinutes();
+        var seconds = now.getSeconds();
+        var hundredths = (now.getMilliseconds() / 10);
+
+        _bits = [];
+
+        shiftBCD(year);
+        shiftBCD(month);
+        shiftBCD(day);
+        shiftBCD(weekday);
+        shiftBCD(hour);
+        shiftBCD(minutes);
+        shiftBCD(seconds);
+        shiftBCD(hundredths);
+    }
+
+    _init();
+
+    function _access(off) {
+        if (off & A2) {
+            _patternIdx = 0;
+        } else {
+            var bit = off & A0;
+            _pattern[_patternIdx++] = bit;
+            if (_patternIdx === 64) {
+                if (_patternMatch()) {
+                    _calcBits();
+                }
+                _patternIdx = 0;
+            }
+        }
+    }
+
+    return {
+        start: function nsc_start()  {
+            return rom.nsc_start();
+        },
+
+        end: function nsc_end() {
+            return rom.nsc_end();
+        },
+
+        read: function nsc_read(page, off) {
+            if (_bits.length > 0) {
+                var bit = _bits.pop();
+                return bit;
+            } else {
+                _access(off);
+            }
+            return rom.read(page, off);
+        },
+
+        write: function nsc_write(page, off, val) {
+            _access(off);
+            rom.write(page, off, val);
+        },
+    };
+}