115 lines
2.9 KiB
ArmAsm
115 lines
2.9 KiB
ArmAsm
;
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; Helper functions for pfs_opendir() and pfs_readdir()
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;
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; Close a directory listing that had been openned by pfs_opendir().
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;
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; 2012-06-01, Ullrich von Bassewitz
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; 2016-04-10, Greg King
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;
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.importzp sp, ptr1, tmp1
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.import pushax, _pfs_read, _pfs_close
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.export __pfs_dirread1, __pfs_dirread
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.export _pfs_closedir
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;---------------------------------------------------------------------------
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; Data structure
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.struct DIR
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fd .word
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.endstruct
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;---------------------------------------------------------------------------
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; /* Read one byte from the directory into the supplied buffer.
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; ** Return true if the read was successful, and false otherwise.
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; */
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; unsigned char __fastcall__ _pfs_dirread1(struct cfs_dir *dir, void *buf);
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__pfs_dirread1:
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jsr pushax ; Push buf
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lda #1 ; Load count = 1
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; Run directly into __dirread
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;---------------------------------------------------------------------------
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; /* Read characters from the directory into the supplied buffer.
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; ** Return true if the read was successful, and false otherwise.
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; */
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; unsigned char __fastcall__ _pfs_dirread(struct cfs_dir *dir, void *buf,
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__pfs_dirread:
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pha ; Save count
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; Replace dir by ((DIR*)dir)->fd.
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ldy #$02
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lda (sp),y
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sta ptr1
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iny
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lda (sp),y
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sta ptr1+1
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ldy #DIR::fd+1
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lda (ptr1),y
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pha
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dey
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lda (ptr1),y
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ldy #$02
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sta (sp),y
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pla
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iny
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sta (sp),y
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; Get count, save it again, clear the high byte, and call pfs_read().
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; By the previous actions, the stack frame is as pfs_read() needs it;
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; and, pfs_read() also will drop it.
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pla
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pha
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ldx #>$0000
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jsr _pfs_read
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; Check for errors.
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cpx #>-1
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beq L3
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; pfs_read() was successful; check number of bytes read. We assume that
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; pfs_read() will not return more than count; so, .X is zero if we come here.
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sta tmp1 ; Save returned count
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pla ; Our count
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cmp tmp1
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beq L2 ; OK, return count
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; Didn't read enough bytes. That is an error for us.
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bne L1 ; Branch always
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; pfs_read() returned an error.
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L3: pla ; Drop count
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inx ; .X = 0
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L1: txa ; Return zero
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L2: rts
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;---------------------------------------------------------------------------
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; void __fastcall__ pfs_closedir(struct cfs_dir *dirp);
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.proc _pfs_closedir
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sta ptr1
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stx ptr1+1
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; Load ((DIR *)dirp)->fd.
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ldy #DIR::fd+1
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lda (ptr1),y
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tax
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dey
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lda (ptr1),y
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; Close the directory file.
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jmp _pfs_close
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.endproc
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