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56 lines
1.0 KiB
ArmAsm
56 lines
1.0 KiB
ArmAsm
;
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; Christian Groessler, October 2000
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;
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; this file provides the _dio_read function
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;
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; unsigned char __fastcall__ _dio_read(_driveid_t drive_id, _sectnum_t sect_num, void *buffer);
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; _driveid_t - 8bit
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; _sectnum_t - 16bit
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;
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.export __dio_read
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.import popa,popax
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.include "atari.inc"
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.proc __dio_read
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sta DBUFLO ; set buffer address into DCB
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stx DBUFHI
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jsr popax
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sta DAUX1 ; set sector #
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stx DAUX2
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jsr popa
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cmp #16
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bcs _inv_dev ; invalid device #
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adc #1
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sta DUNIT ; unit number (d1,d2,d3,...)
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lda #$31 ; D1 (drive_id == 0) has id $31
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sta DDEVIC
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lda #0
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sta DBYTHI ; high byte of bytes to transfer
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lda #%01000000 ; indicate i/o direction (read)
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sta DSTATS
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lda #15
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sta DTIMLO ; value got from DOS source
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lda #128
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sta DBYTLO ; low byte of bytes to transfer
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lda #SIO_READ ; read sector
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sta DCOMND
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jsr SIOV ; execute
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ldx #0
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lda DSTATS
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bmi _req_err ; error occurred
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txa ; no error occurred
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_req_err:
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rts
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_inv_dev:
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ldx #0
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lda #NONDEV ; non-existent device error
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rts
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.endproc
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