/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifdef SUPPORT_SHA2


LIBHASHSUM_1_NONNULL_
static size_t
process(struct libhashsum_hasher *this, const void *data, size_t bytes)
{
	const uint8_t *m = data;
	int i;
	bytes -= bytes & (this->input_block_size - 1U);
	if (bytes > SIZE_MAX >> 3) {
		for (i = 0; i < 8; i++) {
			libsha2_update(&this->state.sha2.s, m, bytes);
			m = &m[bytes >> 3];
		}
	} else if (bytes) {
		libsha2_update(&this->state.sha2.s, m, bytes << 3);
	}
	return bytes;
}


LIBHASHSUM_1_NONNULL_
static int
finalise_const(struct libhashsum_hasher *this, const void *data, size_t bytes, unsigned extra_bits)
{
	const uint8_t *m = data;
	size_t r;

	if (extra_bits > 7U) {
		errno = EINVAL;
		return -1;
	}

	r = process(this, m, bytes);
	m = &m[r];
	bytes -= r;

	if (!this->hash_output)
		this->hash_output = this->state.sha2.sum;

	libsha2_digest(&this->state.sha2.s, data, (bytes << 3) | extra_bits, this->hash_output);
	memset(&this->state.sha2.s, 0, sizeof(this->state.sha2.s));
	return 0;
}


LIBHASHSUM_1_NONNULL_
static int
finalise(struct libhashsum_hasher *this, void *data, size_t bytes, unsigned extra_bits, size_t size)
{
	(void) size;
	return finalise_const(this, data, bytes, extra_bits);
}


int
libhashsum_init_sha2_hasher(struct libhashsum_hasher *this, unsigned algobits, size_t hashbits)
{
	enum libsha2_algorithm algo;

	if (algobits == 32U && hashbits == 224U) {
		this->algorithm = LIBHASHSUM_SHA_224;
		algo = LIBSHA2_224;
		this->algorithm_string = "SHA-224";
	} else if (algobits == 32U && hashbits == 256U) {
		this->algorithm = LIBHASHSUM_SHA_256;
		algo = LIBSHA2_256;
		this->algorithm_string = "SHA-256";
	} else if (algobits == 64U && hashbits == 384U) {
		this->algorithm = LIBHASHSUM_SHA_384;
		algo = LIBSHA2_384;
		this->algorithm_string = "SHA-384";
	} else if (algobits == 64U && hashbits == 512U) {
		this->algorithm = LIBHASHSUM_SHA_512;
		algo = LIBSHA2_512;
		this->algorithm_string = "SHA-512";
	} else if (algobits == 64U && hashbits == 224U) {
		this->algorithm = LIBHASHSUM_SHA_512_224;
		algo = LIBSHA2_512_224;
		this->algorithm_string = "SHA-512/224";
	} else if (algobits == 64U && hashbits == 256U) {
		this->algorithm = LIBHASHSUM_SHA_512_256;
		algo = LIBSHA2_512_256;
		this->algorithm_string = "SHA-512/256";
	} else {
		errno = EINVAL;
		return -1;
	}

	this->input_block_size = (size_t)algobits << 1;
	this->hash_size = hashbits >> 3;
	this->hash_output = NULL;
	this->supports_non_whole_bytes = 1;
	this->standard_partial_byte_input_encoding = LIBHASHSUM_LEAST_SIGNIFICANT;
	this->standard_partial_byte_output_encoding = LIBHASHSUM_UNSUPPORTED;
	this->hash_excess_bits = 0;
	this->relative_performance = (algobits == 32U ? 277891737809888154ULL : 32055903736688859ULL);
	this->process = &process;
	this->finalise_const = &finalise_const;
	this->finalise = &finalise;
	this->stretch = NULL;
	this->destroy = NULL;
	libsha2_init(&this->state.sha2.s, algo);
	return 0;
}


#else
int
libhashsum_init_sha2_hasher(struct libhashsum_hasher *this, unsigned algobits, size_t hashbits)
{
	(void) this;
	(void) algobits;
	(void) hashbits;
	errno = ENOSYS;
	return -1;
}
#endif