Short: Redirects any (hw-banging) sound program to AHI Author: Martin Blom Uploader: Martin Blom Type: driver/audio Version: 0.3 Requires: An MMU, 68020+, AHI v4, OS 3.5 for GUI mode Architecture: m68k-amigaos Q: What is "Nalle Puh"? A: It's the Swedish name for Winnie the Pooh. Q: Really? A: Yup. Q: But... Ehm. What does this program, "Nalle PUH", do? A: It's a hack that intercepts some custom chip register accesses and turns them into AHI function calls. Q: How? A: By using the MMU to mark the page at $dff000 as invalid. Q: Invalid? Doesn't that mean you will get an exception each time the OS or an application touches the registers? A: Exactly. Q: Isn't that kind of... slow? A: You bet. Q: How slow? A: Unbearable. Q: So the program is useless, then? A: Not quite. It can be instructed to patch the OS and all applications that read or write to the custom chip registers, so that next time the instruction is executed, no exception will be generated. Q: How? A: A new chip register area is created at $80dff000. For the kickstart ROM, all modules except audio.device will be patched to access this address instead of $dff000. For applications, I simply guess when it's ok to patch the instructions. Q: Is that fool-proof? A: Of course not. It's a hack. A proof of concept. Nothing more. Q: Alright then. So what programs can be redirected? A: I've tried the following programs, and they seem to work: * audio.device * Digibooster 1.7 * Musicline Editor 1.5 * Octamed Soundstudio 1.03c * Protracker (version 2.3 and 4.0) * THX Sound System 2.3d. I've also tried the following, and they don't: * Delitracker 2.32 * Newtracker * PlaySID (Note that Protracker disables multitasking and cannot be used with AHI drivers that are not interrupt based.) Previously, I wrote that Sid4Amiga also could be redirected, which is just plain stupid, since Sid4Amiga already uses AHI. Duh! Sorry, Paul. Q: Will you extend Nalle PUH so the all of those program work? A: Unlikely. Q: Pretty, pretty please! A: No. The source code is available. Why don't you give it a shot yourself? Q: Because . A: Too bad. Q: Suppose I do fix the program, is there anything else I should do? A: You could certanly improve the instruction patching method. And it could also be wise to set up a cachable Chip-RAM mirror so AHI won't have to mix the samples from a non-cachable memory area. Q: Hey! I found a memory leak: You don't close mmu.library! And you don't clean up the MMU tables fully either. A: I know. The custom chip register mirror must stay if applications were patched. mmu.library must not be flushed from memory, or we loose the mirror. Version history: 0.1, 2001-04-23: * Initial release. 0.2, 2001-04-28: * Redirected logging to the listview in GUI mode. * Minor GUI updates. 0.3, 2001-05-04 * Clears insr. caches when patching applications. * Added a few more instr. patches (base relative). This means that I had to move the register mirror to $e00000. At least that area is unused on my A4000. * The GUI does not touch the Paula registers on exit, unless the user has pressed "Test" at least once. * Final update! I've returned the sound card I borrowed to write this hack. Thus, no more updates.