;
-; Ullrich von Bassewitz, 22.11.2002
+; Ullrich von Bassewitz, 2002-11-22, 2004-05-14
;
-; size_t __fastcall__ fread (void* buf, size_t size, size_t count, FILE* f);
+; size_t __fastcall__ fread (void* buf, size_t size, size_t count, FILE* file);
; /* Read from a file */
;
.export _fread
.import _read
- .import pushax, incsp6, addysp, ldaxysp, pushwysp, return0
+ .import pusha0, pushax
+ .import incsp4, incsp6
+ .import ldaxysp, ldax0sp
+ .import pushwysp
.import tosumulax, tosudivax
- .importzp ptr1, tmp1
+ .importzp ptr1, sp
.include "errno.inc"
.include "_file.inc"
+ .macpack generic
; ------------------------------------------------------------------------
; Code
.proc _fread
-; Save f and place it into ptr1
+; We will place a pointer to the file descriptor into the register bank
- sta f
- sta ptr1
- stx f+1
- stx ptr1+1
+ .import regbank: zp
+ file = regbank
-; Check if the file is open
+; Save two bytes from the register bank
+
+ ldy file+0
+ sty save
+ ldy file+1
+ sty save+1
- ldy #_FILE_f_flags
- lda (ptr1),y
- and #_FOPEN ; Is the file open?
- bne @L2 ; Branch if yes
+; Save the file pointer into the register bank
-; File not open
+ sta file
+ stx file+1
+
+; Check if the file is open
- lda #EINVAL
- sta __errno
- lda #0
- sta __errno+1
-@L1: jsr incsp6
- jmp return0
+ ldy #_FILE::f_flags
+ lda (file),y
+ and #_FOPEN ; Is the file open?
+ beq @L1 ; Branch if no
; Check if the stream is in an error state
-@L2: lda (ptr1),y ; get f->f_flags again
- and #_FERROR
- bne @L1
+ lda (file),y ; get file->f_flags again
+ and #_FERROR
+ beq @L2
+
+; File not open or in error state
+
+@L1: lda #EINVAL
+ jsr __seterrno ; Set __errno, return zero in A
+ tax ; a/x = 0
+ jmp @L99 ; Bail out
+
+; Remember if we have a pushed back character and reset the flag.
+
+@L2: tax ; X = 0
+ lda (file),y
+ and #_FPUSHBACK
+ beq @L3
+ lda (file),y
+ and #<~_FPUSHBACK
+ sta (file),y ; file->f_flags &= ~_FPUSHBACK;
+ inx ; X = 1
+@L3: stx pb
; Build the stackframe for read()
- ldy #_FILE_f_fd
- lda (ptr1),y
- ldx #$00
- jsr pushax ; f->f_fd
+ ldy #_FILE::f_fd
+ lda (file),y
+ jsr pusha0 ; file->f_fd
ldy #9
jsr pushwysp ; buf
-; Stack is now: buf/size/count/f->fd/buf
+; Stack is now: buf/size/count/file->fd/buf
; Calculate the number of bytes to read: count * size
ldy #7
jsr ldaxysp ; Get size
jsr tosumulax ; count * size -> a/x
-; Check if the number of bytes is zero. Don't call read in this case
+; Check if count is zero.
- cpx #0
- bne @L3
cmp #0
- bne @L3
+ bne @L4
+ cpx #0
+ bne @L4
-; The number of bytes to read is zero, just return count
+; Count is zero, drop the stack frame just built and return count
- ldy #5
- jsr ldaxysp ; Get count
- ldy #10
- jmp addysp ; Drop params, return
+ jsr incsp4 ; Drop file->fd/buf
+ jsr ldax0sp ; Get count
+ jmp @L99 ; Bail out
+
+; Check if we have a buffered char from ungetc
+
+@L4: ldy pb
+ beq @L6
+
+; We have a buffered char from ungetc. Save the low byte from count
+
+ pha
+
+; Copy the buffer pointer into ptr1, and increment the pointer value passed
+; to read() by one, so read() starts to store data at buf+1.
+
+ ldy #0
+ lda (sp),y
+ sta ptr1
+ add #1
+ sta (sp),y
+ iny
+ lda (sp),y
+ sta ptr1+1
+ adc #0
+ sta (sp),y ; ptr1 = buf++;
+
+; Get the buffered character and place it as first character into the read
+; buffer.
+
+ ldy #_FILE::f_pushback
+ lda (file),y
+ ldy #0
+ sta (ptr1),y ; *buf = file->f_pushback;
+
+; Restore the low byte of count and decrement count by one. This may result
+; in count being zero, so check for that.
+
+ pla
+ sub #1
+ bcs @L5
+ dex
+@L5: cmp #0
+ bne @L6
+ cpx #0
+ beq @L8
; Call read(). This will leave the original 3 params on the stack
-@L3: jsr pushax
- jsr _read
+@L6: jsr _read
; Check for errors in read
cpx #$FF
- bne @L5
+ bne @L8
cmp #$FF
- bne @L5
+ bne @L8
-; Error in read. Set the stream error flag and bail out. _oserror and/or
-; errno are already set by read().
+; Error in read. Set the stream error flag and bail out. errno has already
+; been set by read(). On entry to label @L7, X must be zero.
+ inx ; X = 0
lda #_FERROR
-@L4: sta tmp1
- lda f
- sta ptr1
- lda f+1
- sta ptr1+1
- ldy #_FILE_f_flags
- lda (ptr1),y
- ora tmp1
- sta (ptr1),y
- bne @L1 ; Return zero
+@L7: ldy #_FILE::f_flags ; X must be zero here!
+ ora (file),y
+ sta (file),y
+ txa ; a/x = 0
+ beq @L99 ; Return zero
-; Read was ok, check for end of file.
+; Read was ok, account for the pushed back character (if any).
-@L5: cmp #0 ; Zero bytes read?
- bne @L6
+@L8: add pb
+ bcc @L9
+ inx
+
+; Check for end of file.
+
+@L9: cmp #0 ; Zero bytes read?
+ bne @L10
cpx #0
- bne @L6
+ bne @L10
; Zero bytes read. Set the EOF flag
lda #_FEOF
- bne @L4 ; Set flag and return zero
+ bne @L7 ; Set flag and return zero
; Return the number of items successfully read. Since we've checked for
; bytes == 0 above, size cannot be zero here, so the division is safe.
-@L6: jsr pushax ; Push number of bytes read
+@L10: jsr pushax ; Push number of bytes read
ldy #5
jsr ldaxysp ; Get size
jsr tosudivax ; bytes / size -> a/x
+@L99: ldy save ; Restore zp register
+ sty file
+ ldy save+1
+ sty file+1
jmp incsp6 ; Drop params, return
.endproc
; Data
.bss
-f: .res 2
+save: .res 2
+pb: .res 1
projects / cc65 / blobdiff