# HG changeset patch
# User William Astle <lost@l-w.ca>
# Date 1667772027 25200
# Node ID d5ae140d19d454cae47332db23daf234013ec8ef
# Parent  686b600a62eef74e8e9726bfba06eed5becb92c7
Make sure DP is set correcting during IRQ handling

Since DP may have been modified arbitrarily when an IRQ occurs, force it
back to 0 before running the IRQ handler, notably the keyboard code. By
being able to rely on DP being set correctly, the code size and execution
time are both improved somewhat.

diff -r 686b600a62ee -r d5ae140d19d4 src/lwbasic.s
--- a/src/lwbasic.s	Sun Nov 06 14:57:32 2022 -0700
+++ b/src/lwbasic.s	Sun Nov 06 15:00:27 2022 -0700
@@ -452,6 +452,8 @@
                 endc
                 rti
 irqhandler0     lda PIA0.DB                     ; clear VSYNC flag
+                clra                            ; make sure DP is pointing to the right place
+                tfr a,dp
                 bsr keyb_read                   ; go handle the keyboard
                 rti
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