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library: Document VRAM overlap in dual 3D DMA Mode

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Antonio Niño Díaz 2023-10-12 21:11:12 +01:00
parent 53a66ae746
commit 8c323c7e2c
1 changed files with 12 additions and 0 deletions
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source/NEGeneral.c
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@ -546,6 +546,18 @@ void NE_InitConsole(void)
// Framebuffer (one line): 0x06208000 - 0x06208200 (512 B)
// Tile base 2: 0x06208000 - 0x06209000 (4 KB)
// Map base 23: 0x0620B800 - 0x0620C000 (2 KB)
//
// There is an overlap between the framebuffer and the tileset.
// Tileset slots are 16 KB in size, so there is only one tileset
// available in VRAM I. However, bitmap slots are also 16 KB in
// size, so both the bitmap and tileset need to share the same
// space.
//
// Luckily, 256 bytes for a 4 bpp tileset uses the same amount of
// memory as 256 / (8 * 8 * 4 / 8) = 8 tiles. The first characters
// of the console correspond to non-printable ASCII characters, so
// this overlap isn't a real issue as the first 8 characters won't
// ever be shown anyway.
vramSetBankI(VRAM_I_SUB_BG_0x06208000);
consoleInit(0, 1, BgType_Text4bpp, BgSize_T_256x256, 23, 2, false, true);