kst_pio.c File Reference

Cycle counts and divider of the PIO pin driver for the KST wire. More...

#include "kst_pio.h"
#include <stddef.h>
#include <string.h>

Functions
static uint32_t	cycles_of (uint32_t hz, uint32_t ns)
	ns as cycles of hz, rounded to nearest.
static uint32_t	ns_of (uint32_t hz, uint64_t cycles)
	cycles of hz as ns, rounded to nearest.
bool	kst_pio_clock (uint32_t sys_hz, kst_pio_clock_t *out)
	The counts for a system clock of sys_hz.
uint32_t	kst_pio_half_cell_ns (const kst_pio_clock_t *clock)
	The transmit half-cell of clock in ns, rounded to nearest.
uint32_t	kst_pio_tick_ns (const kst_pio_clock_t *clock)
	One tick of clock in ns, rounded up.
static uint32_t	first_sample_cycles (const kst_pio_clock_t *clock)
	Cycles from the last edge to the first sample of the pin, as the pin was when the sample was taken.
unsigned	kst_pio_tx (const kst_pio_clock_t *clock, const kst_frame_t *frame, uint32_t window_ns, uint32_t *words, kst_pio_run_t *run)
	The word stream for frame and a capture until window_ns after its last edge.
void	kst_pio_capture (const kst_pio_clock_t *clock, const kst_pio_run_t *run, const uint32_t *stamps, unsigned n, bool lost, kst_capture_t *out)
	The capture from the n stamps of a transaction, in the order the program gave them.

Detailed Description

Cycle counts and divider of the PIO pin driver for the KST wire.

SPDX-License-Identifier: MIT

Function Documentation

kst_pio_capture()

void kst_pio_capture	(	const kst_pio_clock_t *	clock,
		const kst_pio_run_t *	run,
		const uint32_t *	stamps,
		unsigned	n,
		bool	lost,
		kst_capture_t *	out )

The capture from the n stamps of a transaction, in the order the program gave them.

lost says the program gave more stamps than were kept. A first stamp equal to the window count is a line that was high at the first sample: it sets level0 and is no edge. More than KST_CAP_MAX_EDGES edges, lost, and a stamp no count of the stream can give set overflow.

Parameters

clock	Counts of the clock.
run	Layout of the transaction.
stamps	Stamps the program gave, in order.
n	Number of stamps.
lost	true when the program gave more stamps than were kept.
out	Receives the capture.

kst_pio_clock()

bool kst_pio_clock	(	uint32_t	sys_hz,
		kst_pio_clock_t *	out )

The counts for a system clock of sys_hz.

False when a tick is longer than KST_PIO_MAX_TICK_NS, which it is below 8 MHz, and when the half-cell the clock gives is more than 0.2% from KST_HALF_CELL_NS. Every clock from 9.9MHz up gives one within 0.2%, and a multiple of 5MHz gives it exactly.

Parameters

sys_hz	System clock, in Hz.
out	Receives the counts; left unchanged when false is returned.

Returns

true when the clock gives usable counts.

kst_pio_half_cell_ns()

uint32_t kst_pio_half_cell_ns

(

const kst_pio_clock_t *

clock

)

The transmit half-cell of clock in ns, rounded to nearest.

Parameters

clock

Counts of the clock.

Returns

The transmit half-cell in ns, rounded to nearest.

kst_pio_tick_ns()

uint32_t kst_pio_tick_ns

(

const kst_pio_clock_t *

clock

)

One tick of clock in ns, rounded up.

Parameters

clock

Counts of the clock.

Returns

One tick in ns, rounded up.

kst_pio_tx()

unsigned kst_pio_tx	(	const kst_pio_clock_t *	clock,
		const kst_frame_t *	frame,
		uint32_t	window_ns,
		uint32_t *	words,
		kst_pio_run_t *	run )

The word stream for frame and a capture until window_ns after its last edge.

Returns the number of words written to words, at most KST_PIO_TX_WORDS, or 0 for a frame without half-cells, one longer than KST_FRAME_MAX_HALF_CELLS, or a window that ends before the release.

Parameters

clock	Counts of the clock.
frame	Frame to send.
window_ns	Capture end, in ns after the last edge.
words	Receives the word stream.
run	Receives the layout of the transaction.

Returns

Number of words written, or 0 for a frame that cannot be sent.