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More 8080 improvements, including some initial "Fake CP/M" support

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This commit is contained in:
Jeff Parsons 2016-04-27 08:28:52 -07:00
commit 5b6f6756a2
25 changed files with 1051 additions and 842 deletions
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37
modules/pc8080/lib/bus.js
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@ -78,7 +78,7 @@ function Bus(parmsBus, cpu, dbg)
this.cpu = cpu;
this.dbg = dbg;
this.nBusWidth = parmsBus['buswidth'] || 16;
this.nBusWidth = parmsBus['busWidth'] || 16;
/*
* Compute all Bus memory block parameters, based on the width of the bus.
@ -108,6 +108,7 @@ function Bus(parmsBus, cpu, dbg)
*
* Bus Width Block Shift Block Size
* --------- ----------- ----------
* 16 bits (64Kb address space): 10 1Kb (64 maximum blocks)
* 20 bits (1Mb address space): 12 4Kb (256 maximum blocks)
* 24 bits (16Mb address space): 14 16Kb (1K maximum blocks)
* 32 bits (4Gb address space); 15 32Kb (128K maximum blocks)
@ -119,7 +120,7 @@ function Bus(parmsBus, cpu, dbg)
*/
this.addrTotal = Math.pow(2, this.nBusWidth);
this.nBusLimit = this.nBusMask = (this.addrTotal - 1) | 0;
this.nBlockShift = (this.nBusWidth <= 20)? 12 : (this.nBusWidth <= 24? 14 : 15);
this.nBlockShift = (this.nBusWidth <= 16)? 10 : ((this.nBusWidth <= 20)? 12 : (this.nBusWidth <= 24? 14 : 15));
this.nBlockSize = 1 << this.nBlockShift;
this.nBlockLen = this.nBlockSize >> 2;
this.nBlockLimit = this.nBlockSize - 1;
@ -268,16 +269,15 @@ Bus.prototype.powerUp = function(data, fRepower)
* allocations, etc.
*
* We've relaxed some of the original requirements (ie, that addresses must start at a
* block-granular address, or that sizes must be equal to exactly one or more blocks), because
* machines with large block sizes can make it impossible to load certain ROMs at at their
* required addresses.
* block-granular address, or that sizes must be equal to exactly one or more blocks),
* because machines with large block sizes can make it impossible to load certain ROMs at
* their required addresses. Every allocation still allocates a whole number of blocks.
*
* Even so, Bus memory management does NOT provide a general-purpose heap. Most memory
* allocations occur during machine initialization and never change. The only notable
* exception is the Video frame buffer, which ranges from 4Kb (MDA) to 16Kb (CGA) to
* 32Kb/64Kb/128Kb (EGA), and only the EGA changes its buffer address post-initialization.
* allocations occur during machine initialization and never change. In particular, there
* is NO support for removing partial-block allocations.
*
* Each Memory block keeps track of a single address (addr) and length (used), indicating
* Each Memory block keeps track of a start address (addr) and length (used), indicating
* the used space within the block; any free space that precedes or follows that used space
* can be allocated later, by simply extending the beginning or ending of the previously used
* space. However, any holes that might have existed between the original allocation and an
@ -293,17 +293,18 @@ Bus.prototype.addMemory = function(addr, size, type)
{
var iBlock = addr >>> this.nBlockShift;
while (size > 0 && iBlock < this.aMemBlocks.length) {
var block = this.aMemBlocks[iBlock];
var addrBlock = iBlock * this.nBlockSize;
var sizeBlock = size > this.nBlockSize? this.nBlockSize : size;
var sizeBlock = this.nBlockSize - (addr - addrBlock);
if (sizeBlock > size) sizeBlock = size;
if (block && block.size) {
if (block.type == type) {
/*
* Where there is already a block with a non-zero size, we can allow the allocation only if:
* Where there is already a similar block with a non-zero size, we allow the allocation only if:
*
* 1) addr + size <= block.addr (the request precedes the used portion of the current block)
* or:
* 1) addr + size <= block.addr (the request precedes the used portion of the current block), or
* 2) addr >= block.addr + block.used (the request follows the used portion of the current block)
*/
if (addr + size <= block.addr) {
@ -315,23 +316,27 @@ Bus.prototype.addMemory = function(addr, size, type)
var sizeAvail = block.size - (addr - addrBlock);
if (sizeAvail > size) sizeAvail = size;
block.used = addr - block.addr + sizeAvail;
size -= sizeAvail;
addr = addrBlock + this.nBlockSize;
size -= sizeAvail;
iBlock++;
continue;
}
}
return this.reportError(Bus.ERROR.ADD_MEM_INUSE, addr, size);
}
var blockOld = this.aMemBlocks[iBlock];
var blockNew = new Memory(addr, sizeBlock, this.nBlockSize, type);
blockNew.copyBreakpoints(this.dbg, blockOld);
blockNew.copyBreakpoints(this.dbg, block);
this.aMemBlocks[iBlock++] = blockNew;
addr = addrBlock + this.nBlockSize;
size -= sizeBlock;
}
if (size <= 0) {
return true;
}
return this.reportError(Bus.ERROR.ADD_MEM_BADRANGE, addr, size);
};