[GBS] No sound when playing "Top Gear 2 Pocket"

[brianpow]

No sound when playing "Top Gear 2 Pocket" with gme_player

The gme_player window shows as normal but no sound and only a flat wavefront bar shown

Other GBS player such as NEZPlug and MiniGBS work fine

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[Leandro Nini]

Did a debug trace on MiniGBS:

0242: f0 40    | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | ldh a, [$ff40] | [00]
     * * *     + Audio read : ff40 ->  0                 +                +
0244: cb 7f    | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | bit 7, a       |
0246: 28 09    | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | jr z, +9       |

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It reads from $ff40 (LCD control) and if bit 7 is set enters an infinite loop. Not sure about the rationale

Looking at the other emulators the IO area ($FF00 – $FF7F) is zeroed out at startup, which makes the tune play fine, while on gme it is set to $ff.

Will send a fix later.

[Michael Pyne]

Zero out IO area ($FF00 – $FF7F) at startup. Fixes issue #40

→ <<cset 1991893d9eed>>