87 lines
1.7 KiB
ArmAsm
87 lines
1.7 KiB
ArmAsm
; Function defined on pp272-273 of C64 Programmers Reference Guide
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;; IEC reference at http://www.zimmers.net/anonftp/pub/cbm/programming/serial-bus.pdf
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load:
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;; Disable IRQs, since timing matters!
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SEI
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;; Begin sending under attention
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jsr iec_assert_atn
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;; XXX - Use default device number
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;; http://www.zimmers.net/anonftp/pub/cbm/programming/serial-bus.pdf
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;; p13, 16.
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;; also p16 tells us this routine doesn't mess with the file table in the C64,
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;; only in the drive.
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;; Call device to LISTEN (p16)
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lda #$28
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jsr iec_tx_byte
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bcs load_error
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;; Open channel #0 (p16)
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lda #$f0
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jsr iec_tx_byte
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bcs load_error
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;; (p16)
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jsr iec_release_atn
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;; Send filename (p16)
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lda #$24 ; $ = directory
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jsr iec_tx_byte
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;; Command device to unlisten to indicate end of file name. (p16)
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jsr iec_assert_atn
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lda #$3f
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jsr iec_tx_byte
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bcs load_error
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jsr iec_release_atn
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;; Now command device to talk (p16)
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jsr iec_assert_atn
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lda #$48
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jsr iec_tx_byte
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bcs load_error
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lda #$60 ; open channel / data (p3) , required according to p13
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jsr iec_tx_byte
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bcs load_error
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jsr iec_release_atn
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;; We are currently talker, so do the IEC turn around so that we
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;; are the listener (p16)
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jsr iec_turnaround_to_listen
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bcs load_error
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;; We are now ready to receive bytes
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;; jsr iec_rx_byte
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;; bcs load_done
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load_done:
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;; Close file on drive
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;; Command drive to listen and to close the file
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jsr iec_assert_atn
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lda #$28
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jsr iec_tx_byte
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lda #$e0
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jsr iec_tx_byte
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jsr iec_release_atn
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;; Tell drive to unlisten
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jsr iec_assert_atn
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lda #$3f
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jsr iec_tx_byte
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jsr iec_release_atn
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;; FALL THROUGH
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load_error:
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;; Re-enable interrupts and return
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cli
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;; (iec_tx_byte will have set/cleared C flag and put result code
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;; in A if it was an error).
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rts
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