159 lines
3.3 KiB
ArmAsm
159 lines
3.3 KiB
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# M65 KERNAL_1 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// Tape (turbo) part of the LOAD routine
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//
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// Initially based on routine by enthusi/Onslaught, found here:
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// - https://codebase64.pokefinder.org/doku.php?id=base:turbotape_loader_source
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// but heavily reworked since then. Still, original authors deserve credits!
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#if CONFIG_TAPE_TURBO
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#if !CONFIG_TAPE_AUTODETECT
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load_tape_turbo:
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#else
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load_tape_auto:
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#endif
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jsr tape_ditch_verify // only LOAD is supported, no VERIFY
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// Prepare for sound effects
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jsr tape_clean_sid
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// Start playing
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jsr tape_common_prepare_cia
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jsr tape_ask_play
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// FALLTROUGH
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#if CONFIG_TAPE_AUTODETECT
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load_tape_turbo_takeover: // entry point for normal->turbo takeover
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jsr tape_common_autodetect
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bcc_16 load_tape_normal_takeover
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#endif
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// FALLTROUGH
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load_tape_turbo_header:
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// Read file header; structure described here:
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// - https://www.luigidifraia.com/c64/docs/tapeloaders.html#turbotape64
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//
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// 1 byte - file type (0 = data, odd value = relocatable, even value = non-relocatable)
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// 2 bytes - start address
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// 2 bytes - end address + 1
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// 1 byte - if $B0 (tape timing) contained at the time of saving
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// (we skip this one to match normal system header)
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// 16 bytes - filename, padded with 0x20
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jsr tape_turbo_sync_header
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#if CONFIG_TAPE_AUTODETECT
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bcs_16 load_tape_normal_takeover // failure, probably not a turbo tape file
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#endif
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ldy #$00
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sta (TAPE1), y // store header type
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iny
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// FALLTROUGH
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load_tape_turbo_header_loop:
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jsr tape_turbo_get_byte
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sta (TAPE1), y
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iny
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cpy #$05
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bne !+
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jsr tape_turbo_get_byte // tape timing - skip this one
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!:
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cpy #$C0 // header is 192 bytes long in total
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bne load_tape_turbo_header_loop
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// For non-relocatable files, override secondary address
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ldy #$00 // XXX optimize out for 65C02
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lda (TAPE1), y
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beq !+
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and #$01
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bne !+
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lda #$01 // XXX for 65C02 just set the bit with one instruction
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sta SA
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!:
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// Handle the header
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jsr tape_clean_sid
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jsr tape_handle_header
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bcs load_tape_turbo_header // if name does not match, look for other header
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// FALLTROUGH
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load_tape_turbo_payload:
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// Copy helper byte store routine to RAM, provide default memory mapping
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ldx #(__tape_turbo_bytestore_size - 1)
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!:
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lda tape_turbo_bytestore_source, x
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sta __tape_turbo_bytestore, x
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dex
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bpl !-
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lda CPU_R6510
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sta __tape_turbo_bytestore_defmap
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// Initial checksum value
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lda #$00
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sta PRTY
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// Read file payload
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!:
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jsr tape_turbo_sync_payload
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#if CONFIG_TAPE_AUTODETECT
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bcs !-
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#endif
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// FALLTROUGH
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load_tape_turbo_loop:
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jsr tape_turbo_get_byte
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jsr __tape_turbo_bytestore // like 'sta (MEMUSS),y' - but under I/O
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eor PRTY // handle checksum
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sta PRTY
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// Advance MEMUSS (see Mapping the C64, page 36)
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#if !HAS_OPCODES_65CE02
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jsr lvs_advance_MEMUSS
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#else
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inw MEMUSS+0
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#endif
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jsr lvs_check_EAL
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bne load_tape_turbo_loop
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// Get the checksum
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jsr tape_turbo_get_byte
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tax
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// Silence audio
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jsr tape_clean_sid
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// Verify the checksum
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cpx PRTY
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beq_16 tape_load_success
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jmp tape_load_error
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#endif // CONFIG_TAPE_TURBO
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