git.joshuawise.com / fpgaboy.git / blame
| Commit | Line | Data |
|---|---|---|
| 2bcaaabf JW |
1 | SECTION "wee",HOME[$0] |
| 2 | ; this all needs to be PIC! | |
| bf3f2c5f JW |
3 | ; xor a |
| 4 | ; ld hl, $FF60 | |
| 5 | ; ld [hli], a | |
| 6 | ; ld [hli], a | |
| 7 | ; ld [hli], a | |
| 8 | st: ld sp, $CFFF | |
| 2bcaaabf JW |
9 | nak: |
| 10 | ld a, $15 ; NAK | |
| 11 | call putc+$FF80 | |
| 12 | ||
| 13 | .ack: call getc+$FF80 | |
| bf3f2c5f JW |
14 | ; cp $01 ;SOH |
| 15 | ; jr z,.soh | |
| 2bcaaabf JW |
16 | cp $04 ;EOT |
| 17 | jr z, .eot | |
| 18 | cp $18 ;CAN | |
| 19 | jr z, .rst | |
| bf3f2c5f | 20 | jr nak |
| 2bcaaabf JW |
21 | |
| 22 | .eot: | |
| 23 | ld A, $06 ; Ack the EOT | |
| 24 | call putc+$FF80 | |
| 25 | .rst: rst $00 | |
| 26 | ||
| 27 | .soh: call getc+$FF80 ; blk | |
| 28 | call getc+$FF80 ; iblk | |
| bf3f2c5f JW |
29 | ld b, $00 |
| 30 | ld hl, $C000 | |
| 31 | .lp: bit 7, l | |
| 32 | jr nz, .cksm | |
| 33 | call getc+$FF80 | |
| 2bcaaabf JW |
34 | ld [hli], a |
| 35 | add b | |
| 36 | ld b, a | |
| bf3f2c5f | 37 | jr .lp |
| 2bcaaabf JW |
38 | .cksm: call getc+$FF80 |
| 39 | cp b | |
| 40 | jr nz, .donak | |
| 41 | ld hl, $C000 | |
| bf3f2c5f | 42 | .lp2: ld a, [hli] |
| 2bcaaabf JW |
43 | ld [$FF63], A |
| 44 | bit 7, l | |
| 45 | jr z,.lp2 | |
| bf3f2c5f | 46 | .doack: ld A, $06 ; 06 |
| 2bcaaabf JW |
47 | call putc+$FF80 |
| 48 | jr .ack | |
| 49 | .donak: call getc+$FF80 ; Wait until the line clears, and then once | |
| 50 | jr .donak ; that happens, getc will cause a NAK. | |
| 51 | ||
| 52 | getc: | |
| 53 | xor d | |
| bf3f2c5f | 54 | ;xor e ; Possibly not needed? |
| 2bcaaabf JW |
55 | .dgetc: |
| 56 | dec de | |
| 57 | xor a | |
| 58 | cp d | |
| 59 | jr z, .timeout | |
| 60 | ld a, [$FF53] | |
| 61 | and $02 | |
| 62 | jr z, .dgetc | |
| 63 | ld a, [$FF52] | |
| 64 | ret | |
| 65 | .timeout: | |
| bf3f2c5f | 66 | ld hl, $D010 |
| 2bcaaabf JW |
67 | ld a, [hl] |
| 68 | inc a | |
| 69 | ld [hl], a | |
| 70 | ld [$FF51], a | |
| bf3f2c5f | 71 | pop hl |
| 2bcaaabf JW |
72 | jr nak |
| 73 | ||
| 74 | putc: | |
| 75 | ld c, $53 | |
| 76 | push af | |
| 77 | .waitport: | |
| 78 | ld a,[c] | |
| 79 | and $01 | |
| 80 | jr nz,.waitport | |
| 81 | pop af | |
| 82 | ld [$FF52],a | |
| 83 | ret | |
| 84 | ||
| bf3f2c5f JW |
85 | section "a", HOME[$7E] |
| 86 | nop |