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


/**
 * Unified implementation (what can unified without performance impact)
 * of the chunk processing for all SHA-2 functions
 * 
 * @param  chunk      The data to process
 * @param  A          Wordsize-dependent constant, take a look at the code
 * @param  B          Wordsize-dependent constant, take a look at the code
 * @param  C          Wordsize-dependent constant, take a look at the code
 * @param  D          Wordsize-dependent constant, take a look at the code
 * @param  E          Wordsize-dependent constant, take a look at the code
 * @param  F          Wordsize-dependent constant, take a look at the code
 * @param  G          Wordsize-dependent constant, take a look at the code
 * @param  H          Wordsize-dependent constant, take a look at the code
 * @param  I          Wordsize-dependent constant, take a look at the code
 * @param  J          Wordsize-dependent constant, take a look at the code
 * @param  K          Wordsize-dependent constant, take a look at the code
 * @param  L          Wordsize-dependent constant, take a look at the code
 * @param  WORD_T     `__typeof()` on any wordsize-dependent variable
 * @param  WORD_SIZE  4 for 32-bit algorithms and 8 for 64-bit algorithms
 * @param  TRUNC      `TRUNC32` for 32-bit algorithms and `TRUNC64` for 64-bit algorithms
 * @param  k          Round constants
 * @param  w          Words
 * @param  h          Hash values
 * @param  work_h     Space for temporary hash values
 */
#define SHA2_IMPLEMENTATION(chunk, A, B, C, D, E, F, G, H, I, J, K, L, WORD_T, WORD_SIZE, TRUNC, k, w, h, work_h) \
	memcpy(work_h, h, sizeof(work_h));\
	\
	memset(w, 0, 16 * sizeof(*(w)));\
	for (i = 0; i < 16; i++)\
		for (j = 0; j < WORD_SIZE; j++)\
			w[i] |= ((WORD_T)(chunk[(i + 1) * WORD_SIZE - j - 1])) << (j << 3);\
	\
	for (i = 16; i < sizeof(k) / sizeof(*(k)); i++)	{\
		w[i] = w[i - 16] + w[i - 7];\
		w[i] += ROTR(w[i - 15], A) ^ ROTR(w[i - 15], B) ^ (w[i - 15] >> (C));\
		w[i] += ROTR(w[i - 2], D) ^ ROTR(w[i - 2], E) ^ (w[i - 2] >> (F));\
		w[i] = TRUNC(w[i]);\
	}\
	\
	for (i = 0; i < sizeof(k) / sizeof(*(k)); i++) {\
		s1 = work_h[6] ^ (work_h[4] & (work_h[5] ^ work_h[6]));\
		s1 += work_h[7] + k[i] + w[i];\
		s0 = (work_h[0] & work_h[1]) | (work_h[2] & (work_h[0] | work_h[1]));\
		s1 += ROTR(work_h[4], G) ^ ROTR(work_h[4], H) ^ ROTR(work_h[4], I);\
		s0 += ROTR(work_h[0], J) ^ ROTR(work_h[0], K) ^ ROTR(work_h[0], L);\
		\
		memmove(&work_h[1], work_h, 7 * sizeof(*(work_h)));\
		work_h[4] = TRUNC(work_h[4] + s1);\
		work_h[0] = TRUNC(s1 + s0);\
	}\
	\
	for (i = 0; i < 8; i++)\
		h[i] = TRUNC(h[i] + work_h[i]);


void
libsha2_process(struct libsha2_state *restrict state, const unsigned char *restrict chunk)
{
	if (state->algorithm <= LIBSHA2_256) {
		uint_least32_t s0, s1;
		size_t i, j;

#if defined(__GNUC__)
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wmemset-elt-size"
#endif
#define ROTR(X, N) TRUNC32(((X) >> (N)) | ((X) << (32 - (N))))

		SHA2_IMPLEMENTATION(chunk, 7, 18, 3, 17, 19, 10, 6, 11, 25, 2, 13, 22, uint_least32_t,
		                    4, TRUNC32, state->k.b32, state->w.b32, state->h.b32, state->work_h.b32);

#undef ROTR
#if defined(__GNUC__)
# pragma GCC diagnostic pop
#endif

	} else {
		uint_least64_t s0, s1;
		size_t i, j;

#define ROTR(X, N) TRUNC64(((X) >> (N)) | ((X) << (64 - (N))))

		SHA2_IMPLEMENTATION(chunk, 1, 8, 7, 19, 61, 6, 14, 18, 41, 28, 34, 39, uint_least64_t,
		                    8, TRUNC64, state->k.b64, state->w.b64, state->h.b64, state->work_h.b64);

#undef ROTR
	}
}