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SNES: More accurate behaviour of the last scroll register.

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This commit is contained in:
Angelo Salese 2009-08-06 18:13:49 +00:00
parent fd5ab6e92a
commit aa108566a6
1 changed files with 5 additions and 5 deletions
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10
src/mame/machine/snes.c
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@ -756,14 +756,14 @@ WRITE8_HANDLER( snes_w_io )
snes_ppu.layer[3].data = (data & 0xf0) << 9;
break;
// Anomie says "Current = (Byte<<8) | (Prev&~7) | ((Current>>8)&7);"
// Anomie says "H Current = (Byte<<8) | (Prev&~7) | ((Current>>8)&7); V Current = (Current<<8) | Prev;"
case BG1HOFS: /* BG1 - horizontal scroll (DW) */
snes_ppu.layer[0].offset.horizontal = (data<<8) | (ppu_last_scroll & ~7) | ((snes_ppu.layer[0].offset.horizontal>>8) & 7);
ppu_last_scroll = data;
snes_ppu.update_offsets = 1;
return;
case BG1VOFS: /* BG1 - vertical scroll (DW) */
snes_ppu.layer[0].offset.vertical = (data<<8) | (ppu_last_scroll & ~7) | ((snes_ppu.layer[0].offset.vertical>>8) & 7);
snes_ppu.layer[0].offset.vertical = (data<<8) | (ppu_last_scroll);
ppu_last_scroll = data;
snes_ppu.update_offsets = 1;
return;
@ -773,7 +773,7 @@ WRITE8_HANDLER( snes_w_io )
snes_ppu.update_offsets = 1;
return;
case BG2VOFS: /* BG2 - vertical scroll (DW) */
snes_ppu.layer[1].offset.vertical = (data<<8) | (ppu_last_scroll & ~7) | ((snes_ppu.layer[1].offset.vertical>>8) & 7);
snes_ppu.layer[1].offset.vertical = (data<<8) | (ppu_last_scroll);
ppu_last_scroll = data;
snes_ppu.update_offsets = 1;
return;
@ -783,7 +783,7 @@ WRITE8_HANDLER( snes_w_io )
snes_ppu.update_offsets = 1;
return;
case BG3VOFS: /* BG3 - vertical scroll (DW) */
snes_ppu.layer[2].offset.vertical = (data<<8) | (ppu_last_scroll & ~7) | ((snes_ppu.layer[2].offset.vertical>>8) & 7);
snes_ppu.layer[2].offset.vertical = (data<<8) | (ppu_last_scroll);
ppu_last_scroll = data;
snes_ppu.update_offsets = 1;
return;
@ -793,7 +793,7 @@ WRITE8_HANDLER( snes_w_io )
snes_ppu.update_offsets = 1;
return;
case BG4VOFS: /* BG4 - vertical scroll (DW) */
snes_ppu.layer[3].offset.vertical = (data<<8) | (ppu_last_scroll & ~7) | ((snes_ppu.layer[3].offset.vertical>>8) & 7);
snes_ppu.layer[3].offset.vertical = (data<<8) | (ppu_last_scroll);
ppu_last_scroll = data;
snes_ppu.update_offsets = 1;
return;