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Fixed 2 bugs in the floating bus code.

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The Bulgarian game "Walking in the town" now works.
Also improved the layout of the FB code, and added references to Understanding The Apple IIe for all the important logic and boolean equations used.
This commit is contained in:
nick_westgate 2008-12-30 15:45:48 +00:00
parent eb4be89972
commit 6480ef9b1e
1 changed files with 40 additions and 36 deletions
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62
source/Video.cpp
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@ -680,7 +680,7 @@ void DrawHiResSourceHalfShiftDim ()
2400:83 1---0011 -> 1 1 0 0 half-pixel shift right 2400:83 1---0011 -> 1 1 0 0 half-pixel shift right
2800:06 1---0110 -> 0 1 1 0 column 2 & 3 2800:06 1---0110 -> 0 1 1 0 column 2 & 3
@reference: see Beagle Bro's Disk: "Silicon Salid", File: DOUBLE HI-RES @reference: see Beagle Bro's Disk: "Silicon Salad", File: DOUBLE HI-RES
Fortunately double-hires is supported via pixel doubling, so we can do half-pixel shifts ;-) Fortunately double-hires is supported via pixel doubling, so we can do half-pixel shifts ;-)
*/ */
switch (color) switch (color)
@ -2294,7 +2294,10 @@ DWORD VideoSetSnapshot(SS_IO_Video* pSS)
} }
//=========================================================================== //===========================================================================
//
// References to Jim Sather's books are given as eg:
// UTAIIe:5-7,P3 (Understanding the Apple IIe, chapter 5, page 7, Paragraph 3)
//
WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles) WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles)
{ {
// get video scanner position // get video scanner position
@ -2303,7 +2306,7 @@ WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles)
// machine state switches // machine state switches
// //
int nHires = (SW_HIRES & !SW_TEXT) ? 1 : 0; int nHires = (SW_HIRES && !SW_TEXT) ? 1 : 0;
int nPage2 = (SW_PAGE2) ? 1 : 0; int nPage2 = (SW_PAGE2) ? 1 : 0;
int n80Store = (MemGet80Store()) ? 1 : 0; int n80Store = (MemGet80Store()) ? 1 : 0;
@ -2348,43 +2351,51 @@ WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles)
// calculate scanning memory address // calculate scanning memory address
// //
if (SW_HIRES && SW_MIXED && (v_4 & v_2)) // NICK: Should this be (SW_HIRES && !SW_TEXT) instead of just 'SW_HIRES' ? if (nHires && SW_MIXED && v_4 && v_2) // HIRES TIME signal (UTAIIe:5-7,P3)
{ {
nHires = 0; // (address is in text memory) nHires = 0; // address is in text memory for mixed hires
} }
int nAddend0 = 0x68; // 1 1 0 1 int nAddend0 = 0x0D; // 1 1 0 1
int nAddend1 = (h_5 << 5) | (h_4 << 4) | (h_3 << 3); int nAddend1 = (h_5 << 2) | (h_4 << 1) | (h_3 << 0);
int nAddend2 = (v_4 << 6) | (v_3 << 5) | (v_4 << 4) | (v_3 << 3); int nAddend2 = (v_4 << 3) | (v_3 << 2) | (v_4 << 1) | (v_3 << 0);
int nSum = (nAddend0 + nAddend1 + nAddend2) & (0x0F << 3); int nSum = (nAddend0 + nAddend1 + nAddend2) & 0x0F; // SUM (UTAIIe:5-9)
int nAddress = 0; int nAddress = 0; // build address from video scanner equations (UTAIIe:5-8,T5.1)
nAddress |= h_0 << 0; // a0 nAddress |= h_0 << 0; // a0
nAddress |= h_1 << 1; // a1 nAddress |= h_1 << 1; // a1
nAddress |= h_2 << 2; // a2 nAddress |= h_2 << 2; // a2
nAddress |= nSum; // a3 - aa6 nAddress |= nSum << 3; // a3 - a6
nAddress |= v_0 << 7; // a7 nAddress |= v_0 << 7; // a7
nAddress |= v_1 << 8; // a8 nAddress |= v_1 << 8; // a8
nAddress |= v_2 << 9; // a9 nAddress |= v_2 << 9; // a9
nAddress |= ((nHires) ? v_A : (1 ^ (nPage2 & (1 ^ n80Store)))) << 10; // a10
nAddress |= ((nHires) ? v_B : (nPage2 & (1 ^ n80Store))) << 11; // a11 int p2a = 1 ^ (nPage2 & (1 ^ n80Store));
int p2b = nPage2 & (1 ^ n80Store);
if (nHires) // hires? if (nHires) // hires?
{ {
// Y: insert hires only address bits // Y: insert hires-only address bits
// //
nAddress |= v_A << 10; // a10
nAddress |= v_B << 11; // a11
nAddress |= v_C << 12; // a12 nAddress |= v_C << 12; // a12
nAddress |= (1 ^ (nPage2 & (1 ^ n80Store))) << 13; // a13 nAddress |= p2a << 13; // a13
nAddress |= (nPage2 & (1 ^ n80Store)) << 14; // a14 nAddress |= p2b << 14; // a14
} }
else else
{ {
// N: text, so no higher address bits unless Apple ][, not Apple //e // N: insert text-only address bits
// //
if ((IS_APPLE2) && // Apple ][? nAddress |= p2a << 10; // a10
(kHPEClock <= nHClock) && // Y: HBL? nAddress |= p2b << 11; // a11
(nHClock <= (kHClocks - 1)))
// Apple ][ (not //e) and HBL?
//
if (IS_APPLE2 && // Apple II only (UTAIIe:I-4,#5)
((1 ^ h_5) & ((1 ^ h_3) | (1 ^ h_4)))) // HBL (UTAIIe:8-10,F8.5)
{ {
nAddress |= 1 << 12; // Y: a12 (add $1000 to address!) nAddress |= 1 << 12; // Y: a12 (add $1000; )
} }
} }
@ -2392,14 +2403,7 @@ WORD VideoGetScannerAddress(bool* pbVblBar_OUT, const DWORD uExecutedCycles)
// //
if (pbVblBar_OUT != NULL) if (pbVblBar_OUT != NULL)
{ {
if (v_4 & v_3) // VBL? *pbVblBar_OUT = ((v_4 & v_3) == 0); // VBL' = (v_4 & v_3)' (UTAIIe:5-10,#3)
{
*pbVblBar_OUT = false; // Y: VBL' is false
}
else
{
*pbVblBar_OUT = true; // N: VBL' is true
}
} }
return static_cast<WORD>(nAddress); return static_cast<WORD>(nAddress);
} }