add copious amount of comments

This commit is contained in:
Corwin Kuiper 2021-04-03 18:37:09 +01:00
parent 6a3359c23b
commit bc6f3e6f80

View file

@ -3,15 +3,15 @@
.global InterruptHandlerSimple .global InterruptHandlerSimple
.align .align
InterruptHandlerSimple: InterruptHandlerSimple:
ldr r2, =0x04000200 ldr r2, =0x04000200 @ interrupt enable register location
ldrh r1, [r2] ldrh r1, [r2] @ load 16 bit interrupt enable to r1
ldrh r3, [r2, #2] ldrh r3, [r2, #2] @ load 16 bit interrupt request to r3
and r0, r1, r3 and r0, r1, r3 @ interrupts both enabled and requested
strh r0, [r2, #2] strh r0, [r2, #2] @ store to interrupt request
ldr r2, =0x03007FF8 ldr r2, =0x03007FF8 @ load bios interrupt request location
ldrh r1, [r2] ldrh r1, [r2] @ load bios interrupt requests
orr r1, r1, r0 orr r1, r1, r0 @ or with enabled and requested interrupts
strh r1, [r2] strh r1, [r2] @ acknowlege bios requests
bx lr bx lr @ return to bios