52 lines
1.7 KiB
JavaScript
52 lines
1.7 KiB
JavaScript
/*
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Fabrix - An annotated version of the original JSLinux which is Copyright (c) 2011 Fabrice Bellard
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Clock Emulator
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*/
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function formatter(a) { return ((a / 10) << 4) | (a % 10);}
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function CMOS(PC) {
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var time_array, d;
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time_array = new Uint8Array(128);
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this.cmos_data = time_array;
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this.cmos_index = 0;
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d = new Date();
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time_array[0] = formatter(d.getUTCSeconds());
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time_array[2] = formatter(d.getUTCMinutes());
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time_array[4] = formatter(d.getUTCHours());
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time_array[6] = formatter(d.getUTCDay());
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time_array[7] = formatter(d.getUTCDate());
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time_array[8] = formatter(d.getUTCMonth() + 1);
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time_array[9] = formatter(d.getUTCFullYear() % 100);
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time_array[10] = 0x26;
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time_array[11] = 0x02;
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time_array[12] = 0x00;
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time_array[13] = 0x80;
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time_array[0x14] = 0x02;
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PC.register_ioport_write(0x70, 2, 1, this.ioport_write.bind(this));
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PC.register_ioport_read(0x70, 2, 1, this.ioport_read.bind(this));
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}
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CMOS.prototype.ioport_write = function(mem8_loc, data) {
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if (mem8_loc == 0x70) {
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// the high order bit is used to indicate NMI masking
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// low order bits are used to address CMOS
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// the index written here is used on an ioread 0x71
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this.cmos_index = data & 0x7f;
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}
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};
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CMOS.prototype.ioport_read = function(mem8_loc) {
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var data;
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if (mem8_loc == 0x70) {
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return 0xff;
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} else {
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// else here => 0x71, i.e., CMOS read
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data = this.cmos_data[this.cmos_index];
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if (this.cmos_index == 10)
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// flip the UIP (update in progress) bit on a read
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this.cmos_data[10] ^= 0x80;
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else if (this.cmos_index == 12)
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// Always return interrupt status == 0
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this.cmos_data[12] = 0x00;
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return data;
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}
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};
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