!to "threading.prg",cbm !cpu 6510 ;!source "mylib.a" !macro basic_header .a, .b, .c, .d { *= $0801 !byte <.eol,>.eol,0,0,$9e !text .a, .b, .c, .d .eol: !byte 0,0,0 } num_threads = 2 thread_num = $fd ; current thread number ;-------------------------------------------------------------------------- +basic_header "2", "0", "6", "1" *= $080d init: sei ; set up context switch IRQ lda #$35 sta $01 lda #<context_switch ldx #>context_switch sta $fffe stx $ffff lda #0 sta thread_num cli jmp thread1 ;-------------------------------------------------------------------------- context_switch: pha txa pha tya pha lda $dc0d ; save current thread lda thread_num ; *8 asl asl asl tay ; save A,X,Y pla sta thread_data+6,y pla sta thread_data+5,y pla sta thread_data+4,y ; save PSW pla sta thread_data+1,y ; save PC pla sta thread_data+2,y pla sta thread_data+3,y ; save SP tsx txa sta thread_data,y ; next thread, wraparound ldy thread_num iny cpy #num_threads bne + ldy #0 + sty thread_num ; *8 tya asl asl asl tay ; restore thread data ; stack pointer first lda thread_data,y tax txs ; push PC, PSW for RTI lda thread_data+3,y pha lda thread_data+2,y pha lda thread_data+1,y pha ; push registers lda thread_data+6,y pha lda thread_data+5,y pha lda thread_data+4,y pha pla tay pla tax pla rti ;-------------------------------------------------------------------------- thread1: inc $d021 ldy #$02 jsr wait2 jmp thread1 thread2: inc $d020 ldy #$80 jsr wait2 jmp thread2 wait2: - ldx #0 dex bne *-1 dey bne - rts ;-------------------------------------------------------------------------- thread_data: !fill 8, 0 !byte $ff-$40, $22, <thread2, >thread2, 0,0,0,0
