Trigonometry functions returning 8-bit integer values

Defines
#define	TRIGINT_SIN8_STATIC_TABLE   1
	Compile time macro that can be used to disable the static (compile-time) lookup table.
Functions
uint8_t	trigint_sin8u (trigint_angle_t angle)
	Returns the sine of angle as an unsigned 8-bit integer.
int8_t	trigint_sin8 (trigint_angle_t angle)
	Returns the sine of angle as a signed 8-bit integer.
int	trigint_sin8u_table_size ()
	Returns the size of the lookup table used for unsigned 8-bit integers.
uint8_t	trigint_sin8u_table_lookup (int index)
	Lookup a specific table entry for the given index.
void	trigint_sin8_init ()
	Initialize the dynamic table.

---

Define Documentation

#define TRIGINT_SIN8_STATIC_TABLE   1

Compile time macro that can be used to disable the static (compile-time) lookup table.

This can be used to reduce compiled code size at the expense of requiring a call to trigint_sin8_init() at runtime.

---

Function Documentation

uint8_t trigint_sin8u

(

trigint_angle_t

angle

)

Returns the sine of angle as an unsigned 8-bit integer.

It is scaled to an amplitude of 127 and offset by 128 thus values will range from 1 to 255.

Parameters:

angle

the angle to compute the sine of

Returns:

the sine value, as an unsigned 8-bit integer

See also:

http://en.wikipedia.org/wiki/Offset_binary

int8_t trigint_sin8

(

trigint_angle_t

angle

)

[inline]

Returns the sine of angle as a signed 8-bit integer.

It is scaled to an amplitude of 127 thus values will range from -127 to 127.

Parameters:

angle

the angle to compute the sine of

Returns:

the sine value, as an unsigned 8-bit integer

Note:

There is no table for signed 8-bit computations. It is computed from the unsigned sine value.

int trigint_sin8u_table_size

(

)

Returns the size of the lookup table used for unsigned 8-bit integers.

Returns:

the size of the lookup table used for unsigned 8-bit integers

Note:

This is generally only needed for debugging purposes.

uint8_t trigint_sin8u_table_lookup

(

int

index

)

[inline]

Lookup a specific table entry for the given index.

Parameters:

index

a table index

Returns:

the 8-bit unsigned value at the table entry

Note:

This is generally only needed for debugging purposes.

void trigint_sin8_init

(

)

Initialize the dynamic table.

Must be called before any calls to trigint_sin8u() or trigint_sin8(). This is only necessary and available if the TRIGINT_SIN8_STATIC_TABLE macro is set to 0.