Modules
	interp_config
	Interpolator configurationEach interpolator needs to be configured, these functions provide handy helpers to set up configuration structures.

Functions
void	interp_claim_lane (interp_hw_t *interp, uint lane)
	Claim the interpolator lane specifiedUse this function to claim exclusive access to the specified interpolator lane. More...

void	interp_claim_lane_mask (interp_hw_t *interp, uint lane_mask)
	Claim the interpolator lanes specified in the mask. More...

void	interp_unclaim_lane (interp_hw_t *interp, uint lane)
	Release a previously claimed interpolator lane. More...

bool	interp_lane_is_claimed (interp_hw_t *interp, uint lane)
	Determine if an interpolator lane is claimed. More...

void	interp_unclaim_lane_mask (interp_hw_t *interp, uint lane_mask)
	Release previously claimed interpolator lanes. More...

static void	interp_set_force_bits (interp_hw_t *interp, uint lane, uint bits)
	Directly set the force bits on a specified laneThese bits are ORed into bits 29:28 of the lane result presented to the processor on the bus. There is no effect on the internal 32-bit datapath. More...

void	interp_save (interp_hw_t interp, interp_hw_save_t saver)
	Save the specified interpolator stateCan be used to save state if you need an interpolator for another purpose, state can then be recovered afterwards and continue from that point. More...

void	interp_restore (interp_hw_t interp, interp_hw_save_t saver)
	Restore an interpolator state. More...

static void	interp_set_base (interp_hw_t *interp, uint lane, uint32_t val)
	Sets the interpolator base register by lane. More...

static uint32_t	interp_get_base (interp_hw_t *interp, uint lane)
	Gets the content of interpolator base register by lane. More...

static void	interp_set_base_both (interp_hw_t *interp, uint32_t val)
	Sets the interpolator base registers simultaneouslyThe lower 16 bits go to BASE0, upper bits to BASE1 simultaneously. Each half is sign-extended to 32 bits if that lane’s SIGNED flag is set. More...

static void	interp_set_accumulator (interp_hw_t *interp, uint lane, uint32_t val)
	Sets the interpolator accumulator register by lane. More...

static uint32_t	interp_get_accumulator (interp_hw_t *interp, uint lane)
	Gets the content of the interpolator accumulator register by lane. More...

static uint32_t	interp_pop_lane_result (interp_hw_t *interp, uint lane)
	Read lane result, and write lane results to both accumulators to update the interpolator. More...

static uint32_t	interp_peek_lane_result (interp_hw_t *interp, uint lane)
	Read lane result. More...

static uint32_t	interp_pop_full_result (interp_hw_t *interp)
	Read lane result, and write lane results to both accumulators to update the interpolator. More...

static uint32_t	interp_peek_full_result (interp_hw_t *interp)
	Read lane result. More...

static void	interp_add_accumulater (interp_hw_t *interp, uint lane, uint32_t val)
	Add to accumulatorAtomically add the specified value to the accumulator on the specified lane. More...

static uint32_t	interp_get_raw (interp_hw_t *interp, uint lane)
	Get raw lane valueReturns the raw shift and mask value from the specified lane, BASE0 is NOT added. More...

Detailed Description

Hardware Interpolator API

Each core is equipped with two interpolators (INTERP0 and INTERP1) which can be used to accelerate tasks by combining certain pre-configured simple operations into a single processor cycle. Intended for cases where the pre-configured operation is repeated a large number of times, this results in code which uses both fewer CPU cycles and fewer CPU registers in the time critical sections of the code.

The interpolators are used heavily to accelerate audio operations within the SDK, but their flexible configuration make it possible to optimise many other tasks such as quantization and dithering, table lookup address generation, affine texture mapping, decompression and linear feedback.

Please refer to the RP2040 datasheet for more information on the HW interpolators and how they work.

Function Documentation

◆ interp_add_accumulater()

static void interp_add_accumulater	(	interp_hw_t *	interp,
		uint	lane,
		uint32_t	val
	)

inlinestatic

Add to accumulatorAtomically add the specified value to the accumulator on the specified lane.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1
val	Value to add

Returns: The content of the FULL register

◆ interp_claim_lane()

void interp_claim_lane	(	interp_hw_t *	interp,
		uint	lane
	)

Claim the interpolator lane specifiedUse this function to claim exclusive access to the specified interpolator lane.

This function will panic if the lane is already claimed.

Parameters

interp	Interpolator on which to claim a lane. interp0 or interp1
lane	The lane number, 0 or 1.

◆ interp_claim_lane_mask()

void interp_claim_lane_mask	(	interp_hw_t *	interp,
		uint	lane_mask
	)

Claim the interpolator lanes specified in the mask.

Parameters

interp	Interpolator on which to claim lanes. interp0 or interp1
lane_mask	Bit pattern of lanes to claim (only bits 0 and 1 are valid)

◆ interp_get_accumulator()

static uint32_t interp_get_accumulator	(	interp_hw_t *	interp,
		uint	lane
	)

inlinestatic

Gets the content of the interpolator accumulator register by lane.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1

Returns: The current content of the register

◆ interp_get_base()

static uint32_t interp_get_base	(	interp_hw_t *	interp,
		uint	lane
	)

inlinestatic

Gets the content of interpolator base register by lane.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1 or 2

Returns: The current content of the lane base register

◆ interp_get_raw()

static uint32_t interp_get_raw	(	interp_hw_t *	interp,
		uint	lane
	)

inlinestatic

Get raw lane valueReturns the raw shift and mask value from the specified lane, BASE0 is NOT added.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1

Returns: The raw shift/mask value

◆ interp_lane_is_claimed()

bool interp_lane_is_claimed	(	interp_hw_t *	interp,
		uint	lane
	)

Determine if an interpolator lane is claimed.

Parameters

interp	Interpolator whose lane to check
lane	The lane number, 0 or 1

Returns: true if claimed, false otherwise

See also: interp_claim_lane; interp_claim_lane_mask

◆ interp_peek_full_result()

static uint32_t interp_peek_full_result ( interp_hw_t * interp )

inlinestatic

Read lane result.

Parameters

interp Interpolator instance, interp0 or interp1.

Returns: The content of the FULL register

◆ interp_peek_lane_result()

static uint32_t interp_peek_lane_result	(	interp_hw_t *	interp,
		uint	lane
	)

inlinestatic

Read lane result.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1

Returns: The content of the lane result register

◆ interp_pop_full_result()

static uint32_t interp_pop_full_result ( interp_hw_t * interp )

inlinestatic

Read lane result, and write lane results to both accumulators to update the interpolator.

Parameters

interp Interpolator instance, interp0 or interp1.

Returns: The content of the FULL register

◆ interp_pop_lane_result()

static uint32_t interp_pop_lane_result	(	interp_hw_t *	interp,
		uint	lane
	)

inlinestatic

Read lane result, and write lane results to both accumulators to update the interpolator.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1

Returns: The content of the lane result register

◆ interp_restore()

void interp_restore	(	interp_hw_t *	interp,
		interp_hw_save_t *	saver
	)

Restore an interpolator state.

Parameters

interp	Interpolator instance, interp0 or interp1.
saver	Pointer to save structure to reapply to the specified interpolator

◆ interp_save()

void interp_save	(	interp_hw_t *	interp,
		interp_hw_save_t *	saver
	)

Save the specified interpolator stateCan be used to save state if you need an interpolator for another purpose, state can then be recovered afterwards and continue from that point.

Parameters

interp	Interpolator instance, interp0 or interp1.
saver	Pointer to the save structure to fill in

◆ interp_set_accumulator()

static void interp_set_accumulator	(	interp_hw_t *	interp,
		uint	lane,
		uint32_t	val
	)

inlinestatic

Sets the interpolator accumulator register by lane.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1
val	The value to apply to the register

◆ interp_set_base()

static void interp_set_base	(	interp_hw_t *	interp,
		uint	lane,
		uint32_t	val
	)

inlinestatic

Sets the interpolator base register by lane.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane number, 0 or 1 or 2
val	The value to apply to the register

◆ interp_set_base_both()

static void interp_set_base_both	(	interp_hw_t *	interp,
		uint32_t	val
	)

inlinestatic

Sets the interpolator base registers simultaneouslyThe lower 16 bits go to BASE0, upper bits to BASE1 simultaneously. Each half is sign-extended to 32 bits if that lane’s SIGNED flag is set.

Parameters

interp	Interpolator instance, interp0 or interp1.
val	The value to apply to the register

◆ interp_set_force_bits()

static void interp_set_force_bits	(	interp_hw_t *	interp,
		uint	lane,
		uint	bits
	)

inlinestatic

Directly set the force bits on a specified laneThese bits are ORed into bits 29:28 of the lane result presented to the processor on the bus. There is no effect on the internal 32-bit datapath.

Useful for using a lane to generate sequence of pointers into flash or SRAM, saving a subsequent OR or add operation.

Parameters

interp	Interpolator instance, interp0 or interp1.
lane	The lane to set
bits	The bits to set (bits 0 and 1, value range 0-3)

◆ interp_unclaim_lane()

void interp_unclaim_lane	(	interp_hw_t *	interp,
		uint	lane
	)

Release a previously claimed interpolator lane.

Parameters

interp	Interpolator on which to release a lane. interp0 or interp1
lane	The lane number, 0 or 1

◆ interp_unclaim_lane_mask()

void interp_unclaim_lane_mask	(	interp_hw_t *	interp,
		uint	lane_mask
	)

Release previously claimed interpolator lanes.

See also: interp_claim_lane_mask

Parameters

interp	Interpolator on which to release lanes. interp0 or interp1
lane_mask	Bit pattern of lanes to unclaim (only bits 0 and 1 are valid)

Modules

Functions

Detailed Description

Function Documentation

◆ interp_add_accumulater()

◆ interp_claim_lane()

◆ interp_claim_lane_mask()

◆ interp_get_accumulator()

◆ interp_get_base()

◆ interp_get_raw()

◆ interp_lane_is_claimed()

◆ interp_peek_full_result()

◆ interp_peek_lane_result()

◆ interp_pop_full_result()

◆ interp_pop_lane_result()

◆ interp_restore()

◆ interp_save()

◆ interp_set_accumulator()

◆ interp_set_base()

◆ interp_set_base_both()

◆ interp_set_force_bits()

◆ interp_unclaim_lane()

◆ interp_unclaim_lane_mask()