29 June 2015, 15:32 | #1 |
titan sucks!
Join Date: Dec 2012
Location: munich/germany
Posts: 54
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Copper SKIP after SKIP
Hello,
I'm playing around with Copper SKIPs and JUMPs and I've noticed that a SKIP directly after a successful SKIP is executed though. Copper code is something like: Code:
MOVE SKIP - this one is successful, so it should skip over the next SKIP to JUMP, but he continue just right .... SKIP - here... :-P JUMP Code:
if (cop_state.i1 & 1) { // WAIT or SKIP cop_state.ignore_next = 0; if (cop_state.i2 & 1) cop_state.state = COP_skip_in2; else cop_state.state = COP_wait_in2; #ifdef DEBUGGER if (debug_dma) record_dma (0x8c, cop_state.i2, cop_state.ip - 2, old_hpos, vpos, DMARECORD_COPPER); if (memwatch_enabled) debug_wgetpeekdma_chipram(cop_state.ip - 2, cop_state.i2, MW_MASK_COPPER, 0x8c); #endif } Is that intended and can I find it in the hardware docs? Thanks, neoman |
29 June 2015, 15:42 | #2 |
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 49
Posts: 26,514
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It is correct and matches real hardware.
SKIP does not actually skip anything. It only sets internal variable that causes following MOVE (only if following instruction is MOVE) to do the move to dummy address. MOVE cycle sequence is still the same, "skipped" or not. Nothing happens if following instruction is another SKIP or WAIT. |
29 June 2015, 15:54 | #3 |
titan sucks!
Join Date: Dec 2012
Location: munich/germany
Posts: 54
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Okay, I see. So no way to do negative SKIPs =/
Thanks! |
29 June 2015, 16:46 | #4 |
titan sucks!
Join Date: Dec 2012
Location: munich/germany
Posts: 54
|
Okay, I solved my problems with a sequence like
Code:
SKIP JUMP1 JUMP2 |
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