73 lines
1.1 KiB
ArmAsm
73 lines
1.1 KiB
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# * KERNAL_0 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// Official Kernal routines, described in:
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//
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// - [RG64] C64 Programmers Reference Guide - page 275
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// - [CM64] Computes Mapping the Commodore 64 - page 229
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//
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// CPU registers that has to be preserved (see [RG64]): .Y, .A (see [CM64], page 213)
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//
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CHKIN:
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// Store registers for preservation
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pha
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phy_trash_a
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// Reset status
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jsr kernalstatus_reset
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// First retrieve the FAT/LAT/SAT table index (and check if file is open)
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txa
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jsr find_fls
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bcs_16 chkinout_file_not_open
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// Now we have table index in Y
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lda FAT,Y
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// Handle all the devices
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beq chkin_set_device // 0 - keyboard
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// Tape not supported here
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#if HAS_RS232
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cmp #$02
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beq_16 chkin_rs232
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#endif // HAS_RS232
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#if CONFIG_IEC
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jsr iec_check_devnum_oc
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bcc_16 chkin_iec
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#endif // CONFIG_IEC
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cmp #$03 // screen - only legal one left
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bne_16 chkinout_device_not_present
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chkin_set_device:
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lda FAT,Y
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sta DFLTN
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// FALLTROUGH
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chkinout_end:
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ply_trash_a
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pla
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clc // indicate success
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rts
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chkin_file_not_input:
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ply_trash_a
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pla
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jmp kernalerror_FILE_NOT_INPUT
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