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142 lines
3.3 KiB
ArmAsm
142 lines
3.3 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 22.11.2002
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;
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; size_t __fastcall__ fread (void* buf, size_t size, size_t count, FILE* file);
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; /* Read from a file */
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;
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.export _fread
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.import _read
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.import pushax, incsp6, addysp, ldaxysp, pushwysp, return0
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.import tosumulax, tosudivax
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.importzp ptr1, tmp1
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.include "errno.inc"
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.include "_file.inc"
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; ------------------------------------------------------------------------
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; Code
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.proc _fread
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; Save file and place it into ptr1
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sta file
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sta ptr1
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stx file+1
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stx ptr1+1
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; Check if the file is open
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ldy #_FILE::f_flags
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lda (ptr1),y
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and #_FOPEN ; Is the file open?
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bne @L2 ; Branch if yes
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; File not open
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lda #EINVAL
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sta __errno
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lda #0
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sta __errno+1
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@L1: jsr incsp6
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jmp return0
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; Check if the stream is in an error state
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@L2: lda (ptr1),y ; get file->f_flags again
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and #_FERROR
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bne @L1
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; Build the stackframe for read()
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ldy #_FILE::f_fd
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lda (ptr1),y
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ldx #$00
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jsr pushax ; file->f_fd
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ldy #9
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jsr pushwysp ; buf
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; Stack is now: buf/size/count/file->fd/buf
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; Calculate the number of bytes to read: count * size
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ldy #7
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jsr pushwysp ; count
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ldy #9
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jsr ldaxysp ; Get size
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jsr tosumulax ; count * size -> a/x
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; Check if the number of bytes is zero. Don't call read in this case
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cpx #0
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bne @L3
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cmp #0
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bne @L3
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; The number of bytes to read is zero, just return count
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ldy #5
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jsr ldaxysp ; Get count
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ldy #10
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jmp addysp ; Drop params, return
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; Call read(). This will leave the original 3 params on the stack
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@L3: jsr _read
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; Check for errors in read
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cpx #$FF
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bne @L5
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cmp #$FF
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bne @L5
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; Error in read. Set the stream error flag and bail out. _oserror and/or
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; errno are already set by read().
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lda #_FERROR
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@L4: sta tmp1
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lda file
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sta ptr1
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lda file+1
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sta ptr1+1
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ldy #_FILE::f_flags
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lda (ptr1),y
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ora tmp1
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sta (ptr1),y
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bne @L1 ; Return zero
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; Read was ok, check for end of file.
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@L5: cmp #0 ; Zero bytes read?
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bne @L6
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cpx #0
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bne @L6
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; Zero bytes read. Set the EOF flag
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lda #_FEOF
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bne @L4 ; Set flag and return zero
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; Return the number of items successfully read. Since we've checked for
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; bytes == 0 above, size cannot be zero here, so the division is safe.
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@L6: jsr pushax ; Push number of bytes read
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ldy #5
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jsr ldaxysp ; Get size
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jsr tosudivax ; bytes / size -> a/x
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jmp incsp6 ; Drop params, return
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.endproc
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; ------------------------------------------------------------------------
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; Data
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.bss
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file: .res 2
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