Mercurial > repos > blastem
changeset 2087:3e0801280bef
Implement bitmap to cell mapping feature of 1M mode
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Sat, 05 Feb 2022 23:30:06 -0800 |
| parents | 973a39d93d7b |
| children | c716af3f8980 |
| files | segacd.c |
| diffstat | 1 files changed, 32 insertions(+), 2 deletions(-) [+] |
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--- a/segacd.c Sat Feb 05 16:41:01 2022 -0800 +++ b/segacd.c Sat Feb 05 23:30:06 2022 -0800 @@ -242,12 +242,42 @@ static uint16_t cell_image_read16(uint32_t address, void *vcontext) { - return 0xFFFF; + uint32_t word_of_cell = address & 2; + if (address < 0x10000) { + //64x32 cell view + uint32_t line_of_column = address & 0x3FC; + uint32_t column = address & 0xFC00; + address = (line_of_column << 6) | (column >> 8) | word_of_cell; + } else if (address < 0x18000) { + //64x16 cell view + uint32_t line_of_column = address & 0x1FC; + uint32_t column = address & 0x7E00; + address = 0x10000 | (line_of_column << 6) | (column >> 7) | word_of_cell; + } else if (address < 0x1C000) { + //64x8 cell view + uint32_t line_of_column = address & 0x00FC; + uint32_t column = address & 0x3F00; + address = 0x18000 | (line_of_column << 6) | (column >> 6) | word_of_cell; + } else { + //64x4 cell view + uint32_t line_of_column = address & 0x007C; + uint32_t column = address & 0x1F80; + address &= 0x1E000; + address |= (line_of_column << 6) | (column >> 5) | word_of_cell; + } + m68k_context *m68k = vcontext; + genesis_context *gen = m68k->system; + segacd_context *cd = gen->expansion; + return m68k->mem_pointers[cd->memptr_start_index + 1][address>>1]; } static uint8_t cell_image_read8(uint32_t address, void *vcontext) { - return 0xFF; + uint16_t word = cell_image_read16(address & 0xFFFFFE, vcontext); + if (address & 1) { + return word; + } + return word >> 8; } static void *cell_image_write16(uint32_t address, void *vcontext, uint16_t value)