C64: File I/O support

docs/stdlib/c64.md

@@ -2,14 +2,18 @@
 
 # Commodore 64-oriented modules
 
-## `c64_kernal` module
+## c64_kernal module
 
 The `c64_kernal` module is imported automatically on the C64 target.
+It provides access to Kernal routines, so it requires the Kernal ROM to be enabled.
 
 TODO
 
 ## c64_basic module
 
+The `c64_basic` module provides access to Kernal routines, so it requires the Basic ROM to be enabled.
+In particular, this means that it will not work on cartridge targets without extra preparations.
+
 TODO
 
 ## c64_hardware

docs/stdlib/cbm_file.md

@@ -0,0 +1,81 @@
+[< back to index](../index.md)
+
+## cbm_file
+
+The `cbm_file` module provides support for loading and saving files to tape and disk.
+Currently, it works only for Commodore 64 targets, although support for more targets is coming.
+It uses Kernal routines, so it requires the Kernal ROM to be enabled.
+
+#### byte last_used_device()
+
+Returns the last device number, or 8 if none.
+
+#### void load_file(byte device, pointer name)
+
+Loads a PRG file with the given null-terminated name to the address specified in the file.
+Sets `errno`.
+
+#### void load_file_at(byte device, pointer name, pointer addr)
+
+Loads a PRG file with the given null-terminated name to the given address.
+Sets `errno`.
+
+#### void save_file(byte device, pointer name, pointer start, word length)
+
+Saves `length` bytes starting from `start` to a PRG file named `name` on device `device`.
+Sets `errno`.
+
+#### void exec_disk(byte device, pointer command)
+
+Executes a CBM DOS command on the given drive.
+
+#### void delete_file(byte device, pointer name)
+
+Deletes given file in the given drive. (`S0:`)
+
+#### void rename_file(byte device, pointer old_name, pointer new_name)
+
+Renames given file in the given drive. (`R0:`)
+
+#### void copy_file(byte device, pointer old_name, pointer new_name)
+
+Copies given file in the given drive. (`C0:`)
+
+#### void initialize_disk(byte device)
+
+Reinitialized disk status in the given drive. (`I0`)
+
+#### void validate_disk(byte device)
+
+Validates disk status in the given drive. (`V0`)
+
+#### void format_disk(byte device)
+
+Formats disk status in the given drive. (`N0:`)
+
+#### void open_file(byte device, pointer name, byte fd, byte mode)
+
+Opens a file.
+Sets `errno`.   
+TODO: buggy.
+
+#### const byte MODE_READ = 0
+#### const byte MODE_WRITE = 1
+
+#### void close_file(byte fd)
+
+Closes the given file.
+Sets `errno`.   
+TODO: buggy.
+
+#### byte getbyte_safe()
+
+Reads a byte from file.
+Sets `errno` to `err_eof` when reading the last byte, so don't abort reading when getting `errno != err_ok`.  
+TODO: buggy.
+
+#### void putbyte_safe(byte b)
+
+Wrires a byte from file.
+Sets `errno`.   
+TODO: buggy.

docs/stdlib/string.md

@@ -23,3 +23,8 @@ If the source string is longer than 255 bytes, then the behaviour is undefined (
 
 Converts a null-terminated string to a number.
 Sets `errno`.
+
+#### `void strzappend(pointer buffer, pointer str)`
+#### `void strzappendchar(pointer buffer, byte char)`
+
+Modifies the given null-terminated buffer by appending a null-terminated string or s single character respectively.