/* Copyright (c) Microsoft Corporation.
   Licensed under the MIT License. */
   
#include "sha256.h"

#define ROTL32(a, b) (((a) << (b)) | ((a) >> (32 - (b))))
#define ROTR32(a, b) (((a) >> (b)) | ((a) << (32 - (b))))

#define S0(x) (ROTR32(x, 2) ^ ROTR32(x, 13) ^ ROTR32(x, 22))
#define S1(x) (ROTR32(x, 6) ^ ROTR32(x, 11) ^ ROTR32(x, 25))
#define s0(x) (ROTR32(x, 7) ^ ROTR32(x, 18) ^ (x >> 3))
#define s1(x) (ROTR32(x, 17) ^ ROTR32(x, 19) ^ (x >> 10))

#define a(i) T[(0 - (i)) & 7]
#define b(i) T[(1 - (i)) & 7]
#define c(i) T[(2 - (i)) & 7]
#define d(i) T[(3 - (i)) & 7]
#define e(i) T[(4 - (i)) & 7]
#define f(i) T[(5 - (i)) & 7]
#define g(i) T[(6 - (i)) & 7]
#define h(i) T[(7 - (i)) & 7]

#define blk0(i) (W[i] = data[i])
#define blk2(i) (W[i & 15] += s1(W[(i - 2) & 15]) + W[(i - 7) & 15] + s0(W[(i - 15) & 15]))
#define Ch(x, y, z) (z ^ (x & (y ^ z)))
#define Maj(x, y, z) ((x & y) | (z & (x | y)))

#define R(a, b, c, d, e, f, g, h, i)                               \
    h += S1(e) + Ch(e, f, g) + K[i + j] + (j ? blk2(i) : blk0(i)); \
    d += h;                                                        \
    h += S0(a) + Maj(a, b, c)

#define RX_8(i)                         \
    R(a, b, c, d, e, f, g, h, i);       \
    R(h, a, b, c, d, e, f, g, (i + 1)); \
    R(g, h, a, b, c, d, e, f, (i + 2)); \
    R(f, g, h, a, b, c, d, e, (i + 3)); \
    R(e, f, g, h, a, b, c, d, (i + 4)); \
    R(d, e, f, g, h, a, b, c, (i + 5)); \
    R(c, d, e, f, g, h, a, b, (i + 6)); \
    R(b, c, d, e, f, g, h, a, (i + 7))

static const uint32_t K[64] =
    {
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

static void sha256_transform(uint32_t *state, const uint32_t *data)
{
    uint32_t W[16] = {0};
    uint32_t j;

    uint32_t a, b, c, d, e, f, g, h;
    a = state[0];
    b = state[1];
    c = state[2];
    d = state[3];
    e = state[4];
    f = state[5];
    g = state[6];
    h = state[7];

    for (j = 0; j < 64; j += 16)
    {
        RX_8(0);
        RX_8(8);
    }

    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
    state[4] += e;
    state[5] += f;
    state[6] += g;
    state[7] += h;
}

static void sha256_write_byte_block(sha256_t *p)
{
    uint32_t data32[16];
    for (unsigned i = 0; i < 16; i++)
    {
        data32[i] =
            ((uint32_t)(p->buffer[i * 4]) << 24) +
            ((uint32_t)(p->buffer[i * 4 + 1]) << 16) +
            ((uint32_t)(p->buffer[i * 4 + 2]) << 8) +
            ((uint32_t)(p->buffer[i * 4 + 3]));
    }

    sha256_transform(p->state, data32);
}

void sha256_init(sha256_t *p)
{
    p->state[0] = 0x6a09e667;
    p->state[1] = 0xbb67ae85;
    p->state[2] = 0x3c6ef372;
    p->state[3] = 0xa54ff53a;
    p->state[4] = 0x510e527f;
    p->state[5] = 0x9b05688c;
    p->state[6] = 0x1f83d9ab;
    p->state[7] = 0x5be0cd19;
    p->count = 0;
}

void sha256_update(sha256_t *p, const unsigned char *data, size_t size)
{
    uint32_t curBufferPos = (uint32_t)p->count & 0x3F;
    while (size > 0)
    {
        p->buffer[curBufferPos++] = *data++;
        p->count++;
        size--;
        if (curBufferPos == 64)
        {
            curBufferPos = 0;
            sha256_write_byte_block(p);
        }
    }
}

void sha256_final(sha256_t *p, unsigned char *digest)
{
    uint64_t lenInBits = (p->count << 3);
    uint32_t curBufferPos = (uint32_t)p->count & 0x3F;
    unsigned i;
    p->buffer[curBufferPos++] = 0x80;

    while (curBufferPos != (64 - 8))
    {
        curBufferPos &= 0x3F;
        if (curBufferPos == 0)
        {
            sha256_write_byte_block(p);
        }
        p->buffer[curBufferPos++] = 0;
    }

    for (i = 0; i < 8; i++)
    {
        p->buffer[curBufferPos++] = (unsigned char)(lenInBits >> 56);
        lenInBits <<= 8;
    }
    sha256_write_byte_block(p);

    for (i = 0; i < 8; i++)
    {
        *digest++ = (unsigned char)(p->state[i] >> 24);
        *digest++ = (unsigned char)(p->state[i] >> 16);
        *digest++ = (unsigned char)(p->state[i] >> 8);
        *digest++ = (unsigned char)(p->state[i]);
    }
    sha256_init(p);
}