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…, and make Fx0A wait for release With jump quirks on, Bxnn added only the low byte of the address to Vx, so jump0 0xE00 with vE at 0x9C landed at 0x09C rather than 0xE9C. The whole twelve bit address counts, including the nibble that names the register. The existing unit test encoded the low byte reading and is updated, with the jump row of Timendus' quirks test as the reference. With clip quirks on, a sprite whose start lay past the edge was not drawn at all. The start always wraps around the screen; clipping only decides what happens to the part that hangs over. That is the ERR2 the quirks test shows on its clipping row. Fx0A resumed when a key went down. The original hardware moves on when the key is released, which the keypad test checks for. The key is now remembered on press and the register written on release. Three unit tests added; one updated.
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The same three things I found in Chip8Python (craigthomas/Chip8Python#51) are in this port, found by reading the same routines. Each is fixed with a unit test.
Quirked jump. With
jump_quirkson,Bxnnadded only the low byte of the address toVx, sojump0 0xE00withvEat0x9Clanded at0x09Cinstead of0xE9C. The whole twelve bit address counts; its top nibble both names the register and is part of the address. The existingtest_jump_index_plus_value_jump_quirksencoded the low byte reading, so it changes with this, with the jump row of Timendus' quirks test as the reference.Clipping. With
clip_quirkson, a sprite whose start position lay past the edge was not drawn at all, because the position was only wrapped when clipping was off. The start always wraps around the screen; clipping only decides what happens to the part that hangs over. That is theERR2the quirks test shows on its clipping row. Fixed in bothdraw_normal_spriteanddraw_extended_sprite.Fx0A. Execution resumed onSDL_KEYDOWN. The original hardware moves on when the key is released, and the keypad test's third check reportsNOT RELEASEDfor this. The key is now remembered on key down in a newkeypress_pendingglobal and the register written on the matchingSDL_KEYUP.Not touched:
Fx29uses the whole register as a character number, andtest_load_sprite_index_integrationasserts that with0x10, so I have left it as you have it.I could not link SDL2, SDL2_mixer and CUnit on this machine, so the changed files have been compiled with
-fsyntax-onlyagainst the SDL 2.30 headers but the test binary has not been run here; the CI run on this pull request is its first. In the Python port the same three fixes took the quirks test from a crash on the SUPER-CHIP path andERR2on clipping to every row passing, and the keypad test fromNOT RELEASEDtoALL GOOD.