From de725da74db5cba0f9bfd0755269e1683423d87b Mon Sep 17 00:00:00 2001 From: user Date: Wed, 15 Jul 2026 23:44:28 +0200 Subject: gbos scaffold: working cooperative microkernel (verified ABAB in emulator) - fix ClearKernelRAM clobbering the kernel stack (only clear $C000-$CBFF) - fix SyscallTrap clobbering DE (buffer arg) during table dispatch - README: run via ~/dev/gbc --headless; note bring-up bugs --- src/tasks.asm | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 src/tasks.asm (limited to 'src/tasks.asm') diff --git a/src/tasks.asm b/src/tasks.asm new file mode 100644 index 0000000..1f84142 --- /dev/null +++ b/src/tasks.asm @@ -0,0 +1,33 @@ +; ============================================================================= +; tasks.asm - two demo userland tasks (text-in-ROM model). +; Each loops: write its letter to the console, then yield. This exercises the +; whole pipeline: syscall trap, console, and the HRAM context switch swapping +; RAM banks / SVBK between tasks. +; ============================================================================= +INCLUDE "include/gbos.inc" + +SECTION "tasks", ROM0 + +TaskA:: +.loop + ld de, .msg + ld b, 1 ; len + ld c, SYS_WRITE + rst $30 + ld c, SYS_YIELD + rst $30 + jr .loop +.msg + db "A" + +TaskB:: +.loop + ld de, .msg + ld b, 1 + ld c, SYS_WRITE + rst $30 + ld c, SYS_YIELD + rst $30 + jr .loop +.msg + db "B" -- cgit v1.3.1-sl0p