24 lines
476 B
ArmAsm
24 lines
476 B
ArmAsm
|
|
iec_wait60us:
|
|
|
|
;; Wait 60usec
|
|
|
|
;; PAL:
|
|
;; - CPU frequency 0.985248 MHz, we need to waste at least 61 cycles
|
|
;; NTSC:
|
|
;; - CPU frequency 1.022727 MHZ, we need to waste at least 59 cycles
|
|
|
|
;; Waste cycles in a loop
|
|
|
|
ldy #$0A ; 2 cycles
|
|
* dey ; 2 cycles * 10
|
|
bpl - ; 3 cycles * 9 + 2 cycles
|
|
rts ; 6 cycles
|
|
|
|
;; 6 cycles JSR to routine,
|
|
;; 57 cycles routine with RTS
|
|
;; 1 cycle to fetch next instruction
|
|
;; ---
|
|
;; 64 cycles
|
|
|