64 lines
1.5 KiB
ArmAsm
64 lines
1.5 KiB
ArmAsm
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;;
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;; Official Kernal routine, described in:
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;;
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;; - [RG64] C64 Programmer's Reference Guide - page 281/282
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;; - [CM64] Compute's Mapping the Commodore 64 - page 229/230
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;; - https://www.pagetable.com/?p=1031, https://github.com/mist64/cbmbus_doc (IEC command)
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;;
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;; CPU registers that has to be preserved (see [RG64]): none
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;;
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close:
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;; XXX this needs more testing (opening 10 files at once, closing in various orders, etc) once the code is more mature
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;; Find the LAT / SAT / FAT entry which LAT corresponds to A
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jsr find_fls
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bcs close_error_not_found ;; XXX can we report error in IOSTATUS here?
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;; We have the entry index in Y - check whether this is IEC device
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lda FAT, y
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jsr iec_devnum_check
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bcs close_remove_from_table
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;; IEC device
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;; First check whether we have something to be sent in the buffer
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lda C3PO
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beq +
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sec ; send it with EOI
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jsr iec_tx_byte ; send the command regardless of the status
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*
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lda SAT, y ; get secondary address
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ora $E0 ; CLOSE command
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sta BSOUR
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jsr iec_tx_command
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bcs close_remove_from_table
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jsr iec_tx_command_finalize
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close_remove_from_table:
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;; Remove channel from the table
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iny
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cpy #$0A
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bpl +
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lda LAT, y
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sta LAT-1, y
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lda FAT, y
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sta FAT-1, y
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lda SAT, y
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sta SAT-1, y
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jmp -
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*
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;; Decrement the list size variable
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dec LDTND
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clc ; report success - not sure if original CLOSE does this, but it's nevertheless a good practice
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rts
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close_error_not_found:
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sec ; report success - not sure if original CLOSE does this, but it's nevertheless a good practice
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rts
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