Factorize file pointer check

libsrc/common/checkferror.s

@@ -0,0 +1,24 @@
+;
+; Colin Leroy-Mira, 2024
+;
+; Helper to check for file opened, not eof, not ferror
+; Expects file pointer in ptr1,
+; Returns with Z flag set if everything is OK,
+; Destroys A, X, Y,
+; Sets file flags in A
+;
+
+        .export         checkferror
+        .importzp       ptr1
+
+        .include        "_file.inc"
+
+checkferror:
+        ldy     #_FILE::f_flags
+        lda     (ptr1),y
+        tax
+        and     #(_FOPEN|_FERROR|_FEOF); Check for file open, error/eof
+        tay
+        txa
+        cpy     #_FOPEN
+        rts

libsrc/common/fgetc.s

@@ -5,7 +5,8 @@
 ;
 
         .export         _fgetc
-        .import         _read, pusha0, pushax, popptr1, incsp2, returnFFFF
+        .import         _read, checkferror
+        .import         pusha0, pushax, popptr1, incsp2, returnFFFF
         .importzp       ptr1
 
         .include        "stdio.inc"
@@ -16,16 +17,10 @@ _fgetc:
         stx     ptr1+1
         jsr     pushax          ; Backup our ptr
 
-        ldy     #_FILE::f_flags
-        lda     (ptr1),y
-        tax
-        and     #_FOPEN         ; Check for file open
-        beq     ret_eof
-        txa
-        and     #(_FERROR|_FEOF); Check for error/eof
+        jsr     checkferror
         bne     ret_eof
 
-        txa
+        tax
         and     #_FPUSHBACK     ; Check for pushed back char
         beq     do_read
 

libsrc/common/fputc.s

@@ -6,7 +6,7 @@
 
         .export         _fputc
         .importzp       ptr1
-        .import         _write
+        .import         _write, checkferror
         .import         pushax, pusha0, popax, incsp2
         .import         pushptr1, popptr1, returnFFFF
 
@@ -21,13 +21,7 @@ _fputc:
         sta     c               ; to return it anyway
         stx     c+1
 
-        ldy     #_FILE::f_flags
-        lda     (ptr1),y
-        tax
-        and     #_FOPEN         ; Check for file open
-        beq     ret_eof
-        txa
-        and     #(_FERROR|_FEOF); Check for error/eof
+        jsr     checkferror
         bne     ret_eof
 
         jsr     pushptr1        ; Backup fp pointer

libsrc/common/fputs.s

@@ -6,7 +6,7 @@
 
         .export         _fputs
         .importzp       ptr1, ptr2
-        .import         _write, _strlen
+        .import         _write, _strlen, checkferror
         .import         swapstk, pushax, returnFFFF
 
         .include        "stdio.inc"
@@ -16,13 +16,7 @@ _fputs:
         sta     ptr1
         stx     ptr1+1
 
-        ldy     #_FILE::f_flags
-        lda     (ptr1),y
-        tax
-        and     #_FOPEN         ; Check for file open
-        beq     ret_eof
-        txa
-        and     #(_FERROR|_FEOF); Check for error/eof
+        jsr     checkferror
         bne     ret_eof
 
         ; Push _write parameters