y16t/lib/idx.c

// SPDX-License-Identifier: ISC
#include "y16t_idx.h"
#include "y16t_internal.h"
#include <arpa/inet.h>
#include <errno.h>
#include <unistd.h>

#include "hilbert.c"

static __attribute__((pure))
uint32_t y16t_table_at(const y16t_idx_t idx, const uint8_t x, const uint8_t y)
{
	return (idx.offset << 12)
	  | (y16t_hilbert_xy2d(1 << 16, x, y) << 2);
}

static __attribute__((pure))
int y16t_idx_hret(const int tmp)
{
	if(tmp == 4) {
		return 0;
	} else if(tmp < 0) {
		return tmp;
	} else {
		return -EIO;
	}
}

int y16t_idx_lookup(
	y16t_idx_t idx,
	uint8_t    x,
	uint8_t    y,
	uint32_t  *result
) {
	const off_t key = y16t_table_at(idx, x, y);
	const int tmp = y16t_idx_hret(y16t_pread_all(idx.fd, result, 4, key));
	if(tmp >= 0) *result = ntohl(*result);
	return tmp;
}

int y16t_idx_update(
	y16t_idx_t     idx,
	const uint8_t  x,
	const uint8_t  y,
	const uint32_t newval
) {
	const off_t key = y16t_table_at(idx, x, y);
	const uint32_t odval = htonl(newval);
	return y16t_idx_hret(y16t_pwrite_all(idx.fd, &odval, 4, key));
}

int y16t_idx_get_or_insert(
	y16t_idx_t    idx,
	const uint8_t x,
	const uint8_t y,
	uint32_t     *value,
	uint32_t    (*palloc)(void*),
	void         *context
) {
	const long key = y16t_table_at(idx, x, y);
	uint32_t value_tmp = 0;
	int tmp = y16t_idx_hret(y16t_pread_all(idx.fd, &value_tmp, 4, key));
	if(tmp < 0)
		return tmp;

	if(!value_tmp) {
		// allocate new entry
		value_tmp = palloc(context);
		if(!value_tmp)
			return -ENOMEM;
		value_tmp = htonl(value_tmp);
		tmp = y16t_idx_hret(y16t_pwrite_all(idx.fd, &value_tmp, 4, key));
	}

	*value = ntohl(value_tmp);
	return tmp;
}

static int y16t_idx_foreach_inner(
	y16t_idx_t idx,
	uint8_t x,
	uint8_t y,
	uint8_t oth,
	int   (*callback)(uint8_t, uint32_t, void*),
	void   *context
) {
	uint32_t value = 0;
	const int tmp = y16t_idx_lookup(idx, x, y, &value);
	if(tmp < 0) return tmp;
	return callback(oth, ntohl(value), context);
}

int y16t_idx_foreach_x(
	y16t_idx_t idx,
	uint8_t    y,
	int      (*callback)(uint8_t, uint32_t, void*),
	void      *context
) {
	for (uint16_t x = 0; x < 0xff; ++x) {
		const int tmp = y16t_idx_foreach_inner(idx, x, y, x, callback, context);
		if(tmp) return tmp;
	}

	return 0;
}

int y16t_idx_foreach_y(
	y16t_idx_t idx,
	uint8_t    x,
	int      (*callback)(uint8_t, uint32_t, void*),
	void      *context
) {
	for (uint16_t y = 0; y < 0xff; ++y) {
		const int tmp = y16t_idx_foreach_inner(idx, x, y, y, callback, context);
		if(tmp) return tmp;
	}

	return 0;
}