basic.h File Reference

BBC BASIC style API. More...

#include <string.h>
#include <stdio.h>
#include "stdint.h"
#include "os.h"

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Functions
static void	CLS (void)
void	COLOUR (uint8_t colour)
void	PLOT (uint8_t plotcode, uint16_t x, uint16_t y)
static void	DRAW (uint16_t x, uint16_t y)
static void	ENVELOPE (const void *block)
void	GCOL (uint8_t action, uint8_t colour)
uint8_t	INKEYNEG (int8_t key)
void	MODE (uint8_t mode)
static void	MOVE (uint16_t x, uint16_t y)
static void	PRINT (const char *string)
void	PRINTTAB (uint8_t x, uint8_t y, const char *string)
void	SOUND (int16_t channel, int16_t amplitude, int16_t pitch, int16_t duration)

Detailed Description

BBC BASIC style API.

C wrappers in the style of BBC BASIC keywords

Function Documentation

CLS()

static void CLS ( void  )

inlinestatic

Clear the text area of the screen

COLOUR()

void COLOUR

(

uint8_t

colour

)

Set the text foreground and background colour

Parameters

colour

0-15 for foreground, 128-143 for background

DRAW()

static void DRAW ( uint16_t  x, uint16_t  y  )

inlinestatic

Draws lines on the screen in MODEs 0,1,2,4 and 5 draws from current graphics point set by MOVE or DRAW previously.

Parameters

x	end of line x coordinate in osunits
y	end of line y coordinate in osunits

ENVELOPE()

static void ENVELOPE ( const void *  block )

inlinestatic

The envelope statement is used with the SOUND statement to control the volume and pitch of a sound while it is playing.

Parameters

block

pointer to 14 byte block containing envelope parameters

GCOL()

void GCOL	(	uint8_t	action,
		uint8_t	colour
	)

Selects the graphics foreground colour and the graphics background colour.

Parameters

action	mode of action to use, 0 = plot, 1 = OR, 2 = AND, 3 = EOR, 4 = invert
colour	logival colour to use

INKEYNEG()

uint8_t INKEYNEG

(

int8_t

key

)

INKEY with a negative number enables you to test whether a particular key is pressed at this instant

key negative key code

Returns

1 if pressed, 0 if not

MODE()

void MODE

(

uint8_t

mode

)

Select which display mode the computer is about to use.

Parameters

mode	number of new mode

MOVE()

static void MOVE ( uint16_t  x, uint16_t  y  )

inlinestatic

moves the graphics cursor to a particular absolute position without drawing a line

Parameters

x	new x coordinate in osunits
y	new y coordinate in osunits

PLOT()

void PLOT	(	uint8_t	plotcode,
		uint16_t	x,
		uint16_t	y
	)

PLOT is the multi-purpose point, line and triangle drawing statement in BASIC. With the graphcis extension ROM fitted, it also provides shape and sprite plotting routines.

It is also the code behind the DRAW and MOVE keywords

Parameters

plotcode	action to perform
x	x coordinate in osunits
y	y coordinate in osunits

PRINT()

static void PRINT ( const char *  string )

inlinestatic

Text output routine

Note this is sumplified from the BASIC version and can only output single zero terminated strings.

Parameters

string

string to output (zero terminated)

PRINTTAB()

void PRINTTAB	(	uint8_t	x,
		uint8_t	y,
		const char *	string
	)

Text output routine at a specific text coordinate

Note this is sumplified from the BASIC version and can only output single zero terminated strings.

Parameters

x	text coordinate
y	text coordinate
string	string to output (zero terminated)

SOUND()

void SOUND	(	int16_t	channel,
		int16_t	amplitude,
		int16_t	pitch,
		int16_t	duration
	)

Generate sounds

Parameters

channel	0-4, 0 = noise channel, 1-3 squarewave
amplitude	loudness -15 (loudest) tp 0 (silence)
pitch	0-255 pitch, A440 = 89, 4 units per semi-tone, 48 per octave
duration	-1 to 254 note duration in 20ths of a second