Apple-2-SW/prog8
1
0
Fork 0
mirror of https://github.com/irmen/prog8.git synced 2026-04-26 20:17:57 +00:00
Code Issues Projects Releases Wiki Activity

added verafx.available()

Browse Source
This commit is contained in:
Irmen de Jong
2023-10-10 20:26:16 +02:00
parent a37769aafe
commit 836bc9d456
3 changed files with 20 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
docs/source/libraries.rst
+5 -2
View File
@@ -521,15 +521,18 @@ Available for the Cx16 target.
Experimental routines that use the new Vera FX logic (hopefully coming in the Vera in new X16 boards,
the emulators already support it).
``available``
Returns true if Vera FX is available, false if not (that would be an older Vera chip)
``mult`` , ``muls``
For now, the hardware 16*16 multiplier is exposed via ``mult`` and ``muls`` routines (unsigned and signed respectively).
The hardware 16*16 multiplier is exposed via ``mult`` and ``muls`` routines (unsigned and signed respectively).
They are about 4 to 5 times faster as the default 6502 cpu routine for word multiplication.
But they depend on some Vera manipulation and 4 bytes in vram just below the PSG registers for storage.
Note: there is a block level %option "verafxmuls" that automatically replaces all word multiplications in that block
by calls to verafx.muls/mult, but be careful with it because it may interfere with other Vera operations or IRQs.
``clear``
There's also a ``clear`` routine here to very quickly clear a piece of vram to a given byte value (it writes 4 bytes at a time).
Very quickly clear a piece of vram to a given byte value (it writes 4 bytes at a time).
The routine is around 3 times faster as a regular unrolled loop to clear vram.
``transparency``