Files
open-roms/c64/kernal/tape/tape_normal_get_pilot.s
T
FeralChild64 d489e7bf41 tape routines can now be placed in Mega65 extra ROM space
commit 2f27e29758da1f1ec965588c0712125051a6f71a
Merge: ba722b1 796b62f
Author: FeralChild64 <you@example.com>
Date:   Tue Jan 28 17:34:53 2020 +0100

    Merge branch 'master' into tape_redirect

commit ba722b17e627af7dd067932688de0a3d86423e37
Author: FeralChild64 <you@example.com>
Date:   Tue Jan 28 17:28:19 2020 +0100

    finished Mega65 variant of tape routines

commit 47de685f2e08576504c5e00a5b7cb78498d22e72
Author: FeralChild64 <you@example.com>
Date:   Mon Jan 27 23:06:45 2020 +0100

    compilation fix

commit c3641acec049a7a6b53c35795b1f9e2df212cec2
Author: FeralChild64 <you@example.com>
Date:   Mon Jan 27 22:53:30 2020 +0100

    dependencies fix

commit dfad7a30bde043fa077005624dde1de4b72573b6
Merge: e4b0ec9 e410bc0
Author: FeralChild64 <you@example.com>
Date:   Mon Jan 27 21:25:49 2020 +0100

    Merge branch 'master' into tape_redirect

commit e4b0ec9c85861bde2ce52e0828d3bf895a681e17
Author: FeralChild64 <you@example.com>
Date:   Sat Jan 25 22:25:20 2020 +0100

    initial attempt to move tape code to Mega65 extra ROM
2020-01-28 17:35:42 +01:00

94 lines
1.7 KiB
ArmAsm

// #LAYOUT# STD * #TAKE
// #LAYOUT# M65 KERNAL_1 #TAKE
// #LAYOUT# * * #IGNORE
//
// Tape (turbo) helper routine - handling the pilot
//
// Injest the pilot - series of short pulses. According to http://sidpreservation.6581.org/tape-format/
// it consist of the following number of pulses:
// - $6A00 for header
// - $1A00 for data and seq block header
// - $4F for repeated header/data
#if CONFIG_TAPE_NORMAL
tape_normal_get_pilot_header: // entry point, reset calibration, require 128x $40 pulses
// Reading the pilot header is the first action performed,
// thus start by setting default thresholds
lda #$91
sta __pulse_threshold
lda #$67
sta __pulse_threshold_ML
lda #$80
skip_2_bytes_trash_nvz
// FALLTROUGH
tape_normal_get_pilot_data: // entry point, require 4x $40 pulses
lda #$04
skip_2_bytes_trash_nvz
// FALLTROUGH
tape_normal_get_pilot_short: // entry point, require 1x $40 pulses
lda #$01
// FALLTROUGH
tape_normal_get_pilot_common:
sta FSBLK
lda #$0B
sta VIC_EXTCOL
// FALLTROUGH
tape_normal_get_pilot_common_restart:
lda FSBLK
sta ROPRTY
// FALLTROUGH
tape_normal_get_pilot_common_loop_outer:
ldy #$40
// FALLTROUGH
tape_normal_get_pilot_common_loop_inner:
jsr tape_common_get_pulse
bcc tape_normal_get_pilot_common_restart // not a pilot - try again
#if CONFIG_TAPE_AUTODETECT
// Try to distinguish turbo by cheecking for short signals
cmp #$B9 // see comment in tape_common_autodetect.s
bcs !+
#endif
jsr tape_normal_calibrate_during_pilot
dey
bne tape_normal_get_pilot_common_loop_inner
dec ROPRTY
bne tape_normal_get_pilot_common_loop_outer
clc
!:
rts
#endif