#include <stdio.h>
#include <stdlib.h>
#include "table.h"

enum loader_status acpi_table_load(const char *path, struct acpi_table **out)
{
	FILE *fp = fopen(path, "rb");
	if (!fp) {
		return LOADER_IOERR;
	}

	fseek(fp, 0, SEEK_END);
	size_t len = ftell(fp);
	fseek(fp, 0, SEEK_SET);

	unsigned char *buf = malloc(len);
	if (!buf) {
		fclose(fp);
		return LOADER_NOMEM;
	}

	size_t r = fread(buf, 1, len, fp);
	if (r != len) {
		free(buf);
		fclose(fp);
		return LOADER_IOERR;
	}

	fclose(fp);

	size_t sum = 0;
	for (size_t i = 0; i < len; i++) {
		sum += buf[i];
	}

	if ((sum % 0x100) != 0) {
		free(buf);
		return LOADER_BADSUM;
	}

	struct acpi_table *table = (struct acpi_table *)buf;
	*out = table;

	return LOADER_OK;
}

void acpi_table_destroy(struct acpi_table *table)
{
	free(table);
}

void acpi_table_get_payload(struct acpi_table *table, void **p, size_t *len)
{
	*p = (unsigned char *)table + sizeof *table;
	*len = table->length;
}

#define STATUS_STRING(code) \
	case code: \
	return #code;

const char *loader_status_string(enum loader_status status)
{
	switch (status) {
	STATUS_STRING(LOADER_OK)
	STATUS_STRING(LOADER_IOERR)
	STATUS_STRING(LOADER_BADSUM)
	STATUS_STRING(LOADER_NOMEM)
	default:
		return "<unknown>";
	}
}