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Handle DMA 16bit channels with 8-bit do_read/write

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The addresses and counts are doubled/left-shifted accordingly
This commit is contained in:
Ernest Wong 2017-11-18 12:49:02 +13:00 committed by Fabian
parent e91c7868d0
commit 3936d75e3a
1 changed files with 35 additions and 6 deletions
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41
src/dma.js
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@ -9,7 +9,8 @@ function DMA(cpu)
/** @const @type {CPU} */
this.cpu = cpu;
this.channel_addr = new Int32Array(8);
this.channel_addr = new Uint16Array(8);
this.channel_page = new Uint8Array(8);
this.channel_count = new Int32Array(8);
this.channel_mask = new Uint8Array(8);
this.channel_mode = new Uint8Array(8);
@ -89,7 +90,7 @@ DMA.prototype.port_addr_write = function(channel, data_byte)
DMA.prototype.port_page_write = function(channel, data_byte)
{
dbg_log("page write [" + channel + "] = " + h(data_byte), LOG_DMA);
this.channel_addr[channel] = this.channel_addr[channel] & 0xFFFF | data_byte << 16;
this.channel_page[channel] = data_byte;
}
DMA.prototype.port_page_read = function(channel)
@ -224,8 +225,8 @@ DMA.prototype.port81_write = function(data_byte)
// read data, write to memory
DMA.prototype.do_read = function(buffer, start, len, channel, fn)
{
var read_count = this.channel_count[channel] + 1,
addr = this.channel_addr[channel];
var read_count = this.count_get_8bit(channel + 1),
addr = this.address_get_8bit(channel);
dbg_log("DMA write channel " + channel, LOG_DMA);
dbg_log("to " + h(addr) + " len " + h(read_count), LOG_DMA);
@ -256,8 +257,8 @@ DMA.prototype.do_read = function(buffer, start, len, channel, fn)
// write data, read memory
DMA.prototype.do_write = function(buffer, start, len, channel, fn)
{
var read_count = this.channel_count[channel],
addr = this.channel_addr[channel];
var read_count = this.count_get_8bit(channel),
addr = this.address_get_8bit(channel);
dbg_log("DMA write channel " + channel, LOG_DMA);
dbg_log("to " + h(addr) + " len " + h(read_count), LOG_DMA);
@ -285,6 +286,34 @@ DMA.prototype.do_write = function(buffer, start, len, channel, fn)
}
}
DMA.prototype.address_get_8bit = function(channel)
{
var addr = this.channel_addr[channel];
// http://wiki.osdev.org/ISA_DMA#16_bit_issues
if(channel >= 5)
{
addr = (addr << 1);
}
addr &= 0xFFFF;
addr |= this.channel_page[channel] << 16;
return addr;
}
DMA.prototype.count_get_8bit = function(channel)
{
var count = this.channel_count[channel];
if(channel >= 5)
{
count *= 2;
}
return count;
}
DMA.prototype.flipflop_get = function(old_dword, new_byte)
{
this.lsb_msb_flipflop ^= 1;