55 lines
1.4 KiB
ArmAsm
55 lines
1.4 KiB
ArmAsm
//
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// Official Kernal routine, described in:
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//
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// - [RG64] C64 Programmer's Reference Guide - page 286
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// - [CM64] Compute's Mapping the Commodore 64 - page 231
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// - IEC reference at http://www.zimmers.net/anonftp/pub/cbm/programming/serial-bus.pdf
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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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// Expects that SETLFS and SETNAM are called before hand.
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// $YYXX = load address.
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// (ignored if SETLFS channel = 1, i.e., like ,8,1)
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// If A=1 then VERIFY instead of LOAD.
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// On exit, $YYXX is the highest address into which data
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// will have been placed.
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// XXX add VERIFY support
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LOAD:
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// Are we loading or verifying?
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sta VERCKK
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// Store start address of LOAD
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lda MEMUSS+0
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sta STAL+0
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lda MEMUSS+1
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sty STAL+1
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// Reset status
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jsr kernalstatus_reset
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#if CONFIG_MEMORY_MODEL_60K
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// We need our helpers to get to filenames under ROMs or IO area
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jsr install_ram_routines
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#endif
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// Check whether we support the requested device
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lda FA
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// Try IEC - legal device numbers for LOAD are 8-30
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// Device numbers above 30 can not be used as IEC (see https://www.pagetable.com/?p=1031),
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// as the protocol combines device number with command code in one byte, above 30 it is
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// no longer possible. Original ROMs show ILLEGAL DEVICE NUMBER error only for devices
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// 0-3; our implementation is more strict here
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cmp #$1F
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bcs !+ // >= 31
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cmp #$08
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bcs_far load_iec // >= 8
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!:
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jmp lvs_illegal_device_number
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