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Commit Graph

39 Commits

Author SHA1 Message Date
Thomas Harte
5d6b5d9f10 Eliminates all emdashes in cross-platform code. 2018-05-13 15:34:31 -04:00
Thomas Harte
0b771ce61a Removes all instances of the copyright symbol. 2018-05-13 15:19:52 -04:00
Thomas Harte
3944e734d3 Ensures full 6845 instance state initialisation and uses an unsigned shifter. 2017-10-17 22:10:28 -04:00
Thomas Harte
edb9fd301c Begins this project's conversion to functional-style casts. 2017-10-03 22:04:15 -04:00
Thomas Harte
b30bb2a234 Adds an initial implementation of display skew, as a completely live property. 2017-08-29 22:16:40 -04:00
Thomas Harte
334afbc710 Removes const from get_status and get_register, as both may now logically mutate the object. 2017-08-27 18:13:55 -04:00
Thomas Harte
17c13624e5 Improved comments. 2017-08-27 18:11:40 -04:00
Thomas Harte
113349d272 Started making some formal admissions that different CRTC models exist. Plenty yet to do. 2017-08-27 18:10:07 -04:00
Thomas Harte
bdda701207 Reverts previous unevidenced change. 2017-08-26 22:58:16 -04:00
Thomas Harte
487fe83dca Ensures that vertical sync and end-of-visible-lines conditions potentially trigger whenever line_counter_ changes, not only when it increments. 2017-08-26 17:54:54 -04:00
Thomas Harte
6c5a03187b Relocates the HSYNC start test, in order to pass Arnold's cpctest HSYNC start position conformance test. 2017-08-26 17:22:48 -04:00
Thomas Harte
7d7aa2f5d5 Eliminates repetition of the unpacking of register 3 into a horizontal sync count. 2017-08-26 14:37:03 -04:00
Thomas Harte
28550c0227 Breaks the 6845 bus cycle into a phase 1 and a phase 2 per the belief that sync line changes, which are observable, happen at the end of the first phase rather than at the beginning of the next. This may have interrupt timing effects, as machines often derive an interrupt from sync. 2017-08-26 13:56:23 -04:00
Thomas Harte
6e99169348 Permits the 6845's bus state to be examined by an owner, eliminating the need to buffer it in the bus handler. But more than that it allows the CRTC to decide when it adjusts the various outputs respective to the main phase. So a net effect of the change is that the CPC now sees vsync a cycle earlier, because my current reading of the 6845 datasheet is that it is set at the end of phase 1, not the beginning of the next phase 1. 2017-08-26 12:59:59 -04:00
Thomas Harte
3caa4705ca Limits sync counter size. 2017-08-26 12:31:19 -04:00
Thomas Harte
039aed1bd1 Switches the two sync counters to upward-going rather than downward, as a more likely match to the way the rest of the 6845 implementation. 2017-08-25 21:26:01 -04:00
Thomas Harte
a914eadc85 Ensured that register 6 is checked on every loop. 2017-08-22 22:17:45 -04:00
Thomas Harte
e956740c56 Refactors the 6845 more clearly to break out the acts of ending a line and ending a frame, changing the way the memory address is altered — the end-of-line value is provisionally stored and then used if necessary — in order to do so. 2017-08-22 21:54:48 -04:00
Thomas Harte
55055c7847 Minor: ensured immediate line comparison works. But I think my problem might be trying to do this as straight line logic? 2017-08-14 19:08:20 -04:00
Thomas Harte
a10389a22c Factored out the stuff of stuffing the bus. 2017-08-14 12:42:22 -04:00
Thomas Harte
a5593bec79 Threw in support for the light-pen trigger. 2017-08-10 15:00:14 -04:00
Thomas Harte
a1e2646301 Imposed counter size limits. 2017-08-10 14:58:24 -04:00
Thomas Harte
6a6e5ae79c Forced users of the 6845 to be explicit about which type. So far with no effect. 2017-08-10 12:28:57 -04:00
Thomas Harte
02d792c003 Simplified logic slightly, avoiding repetition. 2017-08-10 11:48:37 -04:00
Thomas Harte
be8e7a4144 Eliminated false register aliasing, restricted register sizes and locked out reading and writing where appropriate. 2017-08-10 11:22:30 -04:00
Thomas Harte
a4c910f1de This appears to be a more accurate take on 6845 address advancement — it is necessary that character output has finished for the line address to be updated. 2017-08-10 11:12:53 -04:00
Thomas Harte
46278ff297 Experimental: is this meant to be a compare-before-increment? 2017-08-07 23:02:29 -04:00
Thomas Harte
26ce6cdab2 Permitted register 3 to dictate vertical sync length. 2017-08-04 08:56:36 -04:00
Thomas Harte
58b98267fc Formally transferred ownership of PIO accesses to an incoming template, and decided to start being explicit about how to specify the interfaces and provide fallbacks for optional behaviour for the new, clean generation of interfaces. A full-project sweep will inevitably occur but I'll try to tie off this branch first. 2017-08-01 16:15:19 -04:00
Thomas Harte
1d99c116e7 Actually, this is probably more correct: increment and then compare, but increment the refresh address once more after the final character, to avoid repeating it. 2017-08-01 15:29:37 -04:00
Thomas Harte
ee27e16fb1 Switched to post-tests increment. Seems to give proper screen width, but also eliminates that 'compare to +1' step that felt unlikely. 2017-08-01 15:19:25 -04:00
Thomas Harte
3b1db14817 Made a quick attempt at properly updating the refresh address. 2017-08-01 07:36:03 -04:00
Thomas Harte
e3f677fa37 I was under-counting row lines. Adjusted comparison. The emulator now produces a solid white square of approximately correct proportions. I'm sure that filling in pixels will reveal the next set of bugs. 2017-07-31 22:21:46 -04:00
Thomas Harte
5c68b6cc21 Fixed display enable reset when there's no adjustment area. A practical lesson in failure to factor. 2017-07-31 22:16:08 -04:00
Thomas Harte
ffaa627820 Fixed frame restart when there is no adjustment period. 2017-07-31 22:13:45 -04:00
Thomas Harte
5a396f6787 Added an explicit cast. 2017-07-31 22:04:31 -04:00
Thomas Harte
cb0dc7b434 I'm sure it's not going to be this easy, but this is a genuine attempt at full horizontal and vertical timing. 2017-07-31 22:01:54 -04:00
Thomas Harte
e28829bd1b Corrected CRTC timing, gave it someone to talk to and a means with which to talk. 2017-07-31 20:14:46 -04:00
Thomas Harte
68ceeab610 Created a 6845 class and started pushing data at it and clocking it. It doesn't currently have the concept of a bus but will do, hence the in-header implementation. 2017-07-31 19:56:59 -04:00