millfork/docs/stdlib/frequent.md

[< back to index](../doc_index.md)

Definitions on the following list are frequently provided by the default automatically-imported modules. 

However, as they are not the part of the standard library, they might not be available on all targets:

#### `void init_rw_memory()`

Initializes all writable arrays and variables with their initial values.

If the preprocessor feature `INIT_RW_MEMORY` is defined and non-zero,
then `init_rw_memory` is available and should be called before accessing any preinitialized writable object.

If the preprocessor feature `INIT_RW_MEMORY` is not defined or is zero,
then `init_rw_memory` is not available.

#### `void putchar(byte char)`

Prints a single character.

Available for: all computer targets.  
Uses ROM routines, so requires the appropriate ROM to be enabled if applicable.

Note that this function may obey typical platform idiosyncrasies, for example:

* on Commodore PET targets the quote character toggles the quotation mode

* printing past the end of line might insert a blank line below the current one

* printing past the end of the screen might ask the user to confirm scrolling

The exact behaviour is platform-dependent.
Future library versions will strive to eliminate those issues.

#### `void new_line()`

Moves the cursor to the next line.

Available for: all computer targets.  
Uses ROM routines, so requires the appropriate ROM to be enabled if applicable.

#### `pointer readline()`

Reads a line from the console and returns a pointer to a null-terminated string.
The string is valid only until next read from the console.

Available for:
ZX Spectrum,
NEC PC-88,
MSX,
Apple II,
Robotron Z1013 (always trims trailing spaces),
TRS-80,
VIC-20 (except for `vic20_a000`),
Commodore 64 with `c64_basic` module (requires KERNAL and BASIC; empty input is treated like a single space),
Commodore 16 or Plus/4 with `c264_basic` module (requires KERNAL and BASIC; empty input is treated like a single space).

#### `word readword()`

Reads a 16-bit unsigned integer from the console.

Available for:
ZX Spectrum,
NEC PC-88,
MSX,
Apple II,
Robotron Z1013,
TRS-80,
VIC-20 (except for `vic20_a000`),
Commodore 64 with `c64_basic` module (requires KERNAL and BASIC),
Commodore 16 or Plus/4 with `c264_basic` module (requires KERNAL and BASIC).

#### `void bell()`

Beeps.

Available for: Apple 2, ZX Spectrum.
Uses ROM routines, so requires the appropriate ROM to be enabled if applicable.

#### `void set_bg_color(byte color)`

Sets the screen background color.

Available for: C64, VIC-20, C64, C128, C264 series.

#### `void set_border(byte color)`

Sets the screen border color.

Available for: VIC-20, C64, C128, C264 series, ZX Spectrum.

#### `const byte black, white, red, green, blue, cyan, purple, yellow`

Various colour constants.

Available for: VIC-20, C64, C128, C264 series, ZX Spectrum.