diskio read & write routines now always reset the io channels back to the defaults before returning

This means you don't have to call CLRCHN yourself anymore inbetween if you want to do screen output or keyboard input while a file is open

compiler/res/prog8lib/cx16/diskio.p8

@@ -331,6 +331,7 @@ close_end:
             ; optimize for reading just a single byte
             @(bufferpointer) = cbm.CHRIN()
             cx16.r0L = cbm.READST()
+            cbm.CLRCHN()            ; reset default i/o channels
             if cx16.r0L!=0 {
                 f_close()
                 if cx16.r0L & $40 == 0
@@ -358,6 +359,7 @@ close_end:
                 break
             }
         }
+        cbm.CLRCHN()            ; reset default i/o channels
         return list_blocks  ; number of bytes read
 
 byte_read_loop:         ; fallback if MACPTR isn't supported on the device
@@ -377,8 +379,9 @@ m_in_buffer     sta  $ffff
 +
             }}
             cx16.r0L = cbm.READST()
-            if cx16.r0L!=0 {
+            if_nz {
                 f_close()
+                cbm.CLRCHN()            ; reset default i/o channels
                 if cx16.r0L & $40 !=0    ; eof?
                     return list_blocks   ; number of bytes read
                 return 0  ; error.
@@ -386,6 +389,7 @@ m_in_buffer     sta  $ffff
             list_blocks++
             num_bytes--
         }
+        cbm.CLRCHN()            ; reset default i/o channels
         return list_blocks  ; number of bytes read
     }
 
@@ -404,12 +408,13 @@ m_in_buffer     sta  $ffff
             total_read += cx16.r0
             bufferpointer += cx16.r0
         }
+        cbm.CLRCHN()            ; reset default i/o channels
         return total_read
     }
 
     asmsub f_readline(uword bufptr @AY) clobbers(X) -> ubyte @Y, ubyte @A {
         ; Routine to read text lines from a text file. Lines must be less than 255 characters.
-        ; Reads characters from the input file UNTIL a newline or return character (or EOF).
+        ; Reads characters from the input file UNTIL a newline or return character, or 0 byte (likely EOF).
         ; The line read will be 0-terminated in the buffer (and not contain the end of line character).
         ; The length of the line is returned in Y. Note that an empty line is okay and is length 0!
         ; The I/O error status byte is returned in A.
@@ -430,6 +435,9 @@ _line_end   dey     ; get rid of the trailing end-of-line char
             lda  #0
             sta  (P8ZP_SCRATCH_W1),y
 _end        jsr  cbm.READST
+            pha
+            jsr  cbm.CLRCHN
+            pla
             rts
         }}
     }
@@ -478,9 +486,9 @@ _end        jsr  cbm.READST
                 if msb(bufferpointer) == $c0
                     bufferpointer = mkword($a0, lsb(bufferpointer))  ; wrap over bank boundary
                 if cbm.READST()!=0
-                    return false
+                    goto return_status
             } until num_bytes==0
-            return cbm.READST()==0
+            goto return_status
 
 no_mciout:
             ; the device doesn't support MCIOUT, use a normal per-byte write loop
@@ -488,7 +496,10 @@ no_mciout:
                 cbm.CHROUT(@(bufferpointer))
                 bufferpointer++
             }
-            return cbm.READST()==0
+return_status:
+            cx16.r0L = cbm.READST()
+            cbm.CLRCHN()            ; reset default i/o channels
+            return cx16.r0L==0
         }
         return true
     }

compiler/res/prog8lib/shared_cbm_diskio.p8

@@ -309,6 +309,7 @@ close_end:
             ; slightly optimized path for reading just a single byte
             @(bufferpointer) = cbm.CHRIN()
             cx16.r0L = cbm.READST()
+            cbm.CLRCHN()            ; reset default i/o channels
             if cx16.r0L!=0 {
                 f_close()
                 if cx16.r0L & $40 == 0
@@ -334,8 +335,9 @@ m_in_buffer     sta  $ffff
 +
             }}
             cx16.r0L = cbm.READST()
-            if cx16.r0L!=0 {
+            if_nz {
                 f_close()
+                cbm.CLRCHN()            ;  reset default i/o channels
                 if cx16.r0L & $40 !=0    ; eof?
                     return list_blocks   ; number of bytes read
                 return 0  ; error.
@@ -343,6 +345,7 @@ m_in_buffer     sta  $ffff
             list_blocks++
             num_bytes--
         }
+        cbm.CLRCHN()            ; reset default i/o channels
         return list_blocks  ; number of bytes read
     }
 
@@ -359,12 +362,13 @@ m_in_buffer     sta  $ffff
             total_read += cx16.r0
             bufferpointer += cx16.r0
         }
+        cbm.CLRCHN()            ; reset default i/o channels
         return total_read
     }
 
     asmsub f_readline(uword bufptr @AY) clobbers(X) -> ubyte @Y, ubyte @A {
         ; Routine to read text lines from a text file. Lines must be less than 255 characters.
-        ; Reads characters from the input file UNTIL a newline or return character (or EOF).
+        ; Reads characters from the input file UNTIL a newline or return character, or 0 byte (likely EOF).
         ; The line read will be 0-terminated in the buffer (and not contain the end of line character).
         ; The length of the line is returned in Y. Note that an empty line is okay and is length 0!
         ; I/O error status should be checked by the caller itself via READST() routine.
@@ -386,6 +390,9 @@ _line_end   dey     ; get rid of the trailing end-of-line char
             lda  #0
             sta  (P8ZP_SCRATCH_W1),y
 _end        jsr  cbm.READST
+            pha
+            jsr  cbm.CLRCHN
+            pla
             rts
         }}
     }
@@ -438,7 +445,9 @@ _end        jsr  cbm.READST
                 cbm.CHROUT(@(bufferpointer))
                 bufferpointer++
             }
-            return cbm.READST()==0
+            cx16.r0L = cbm.READST()
+            cbm.CLRCHN()            ; reset default i/o channels
+            return cx16.r0L==0
         }
         return true
     }

compiler/res/prog8lib/virtual/diskio.p8

@@ -107,7 +107,7 @@ diskio {
 
     sub f_readline(uword bufptr) -> ubyte {
         ; Routine to read text lines from a text file. Lines must be less than 255 characters.
-        ; Reads characters from the input file UNTIL a newline or return character (or EOF).
+        ; Reads characters from the input file UNTIL a newline or return character, or 0 byte (likely EOF).
         ; The line read will be 0-terminated in the buffer (and not contain the end of line character).
         ; The length of the line is returned. Note that an empty line is okay and is length 0!
         ; The success status is returned in the Carry flag instead: C set = success, C clear = failure/endoffile
@@ -122,7 +122,7 @@ diskio {
                 sys.clear_carry()
                 return size
             } else {
-                if cx16.r0L == '\n' or cx16.r0L=='\r' {
+                if cx16.r0L in ['\n', '\r', 0] {
                     @(bufptr) = 0
                     sys.set_carry()
                     return size

docs/source/libraries.rst

@@ -525,11 +525,6 @@ to see what's in there. (Note: slight variations for different compiler targets)
     You can set the active disk drive number, so it supports multiple drives, just one at a time.
     It does not support reading from more than one file or writing to more than one file at a time.
 
-.. note::
-    If you want to print text to the screen, or do keyboard input, while reading or writing an open file is in progress,
-    you should use ``cbm.CLRCHN()`` before doing so. This resets the default i/o channels to screen and keyboard.
-    Diskio itself is smart enough to set them back to whatever is needed to continue reading/writing with the ``f_read`` or ``f_write`` routines.
-
 .. attention::
     Error handling is peculiar on CBM dos systems (C64, C128, cx16, PET). Read the
     descriptions for the various methods in this library for details and tips.

docs/source/todo.rst

@@ -1,8 +1,6 @@
 TODO
 ====
 
-make a compiler switch to disable footgun warnings  -ignorefootguns
-
 update zsmkit to newest version that includes the on_deck routines when stabilized