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/*

This code is based on the code found from 7-Zip, which has a modified

version of the SHA-256 found from Crypto++ .

The code was modified a little to fit into liblzma and fitz.

This file has been put into the public domain.

You can do whatever you want with this file.

*/

#include "fitz.h"

static inline int isbigendian(void)

{

	static const int one = 1;

	return *(char*)&one == 0;

}

static inline unsigned int bswap32(unsigned int num)

{

	if (!isbigendian())

	{

		return	( (((num) << 24))

			| (((num) << 8) & 0x00FF0000)

			| (((num) >> 8) & 0x0000FF00)

			| (((num) >> 24)) );

	}

	return num;

}

/* At least on x86, GCC is able to optimize this to a rotate instruction. */

#define rotr_32(num, amount) ((num) >> (amount) | (num) << (32 - (amount)))

#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 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 R(i) \

	h(i) += S1(e(i)) + Ch(e(i), f(i), g(i)) + SHA256_K[i + j] \

		+ (j ? blk2(i) : blk0(i)); \

	d(i) += h(i); \

	h(i) += S0(a(i)) + Maj(a(i), b(i), c(i))

#define S0(x) (rotr_32(x, 2) ^ rotr_32(x, 13) ^ rotr_32(x, 22))

#define S1(x) (rotr_32(x, 6) ^ rotr_32(x, 11) ^ rotr_32(x, 25))

#define s0(x) (rotr_32(x, 7) ^ rotr_32(x, 18) ^ (x >> 3))

#define s1(x) (rotr_32(x, 17) ^ rotr_32(x, 19) ^ (x >> 10))

static const unsigned int SHA256_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

transform(unsigned int state[8], const unsigned int data_xe[16])

{

	unsigned int data[16];

	unsigned int W[16];

	unsigned int T[8];

	unsigned int j;

	/* ensure big-endian integers */

	for (j = 0; j < 16; j++)

		data[j] = bswap32(data_xe[j]);

	/* Copy state[] to working vars. */

	memcpy(T, state, sizeof(T));

	/* 64 operations, partially loop unrolled */

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

		R( 0); R( 1); R( 2); R( 3);

		R( 4); R( 5); R( 6); R( 7);

		R( 8); R( 9); R(10); R(11);

		R(12); R(13); R(14); R(15);

	}

	/* Add the working vars back into state[]. */

	state[0] += a(0);

	state[1] += b(0);

	state[2] += c(0);

	state[3] += d(0);

	state[4] += e(0);

	state[5] += f(0);

	state[6] += g(0);

	state[7] += h(0);

}

void fz_sha256_init(fz_sha256 *context)

{

	context->count[0] = context->count[1] = 0;

	context->state[0] = 0x6A09E667;

	context->state[1] = 0xBB67AE85;

	context->state[2] = 0x3C6EF372;

	context->state[3] = 0xA54FF53A;

	context->state[4] = 0x510E527F;

	context->state[5] = 0x9B05688C;

	context->state[6] = 0x1F83D9AB;

	context->state[7] = 0x5BE0CD19;

}

void fz_sha256_update(fz_sha256 *context, const unsigned char *input, unsigned int inlen)

{

	/* Copy the input data into a properly aligned temporary buffer.

	 * This way we can be called with arbitrarily sized buffers

	 * (no need to be multiple of 64 bytes), and the code works also

	 * on architectures that don't allow unaligned memory access. */

	while (inlen > 0)

	{

		const unsigned int copy_start = context->count[0] & 0x3F;

		unsigned int copy_size = 64 - copy_start;

		if (copy_size > inlen)

			copy_size = inlen;

		memcpy(context->buffer.u8 + copy_start, input, copy_size);

		input += copy_size;

		inlen -= copy_size;

		context->count[0] += copy_size;

		/* carry overflow from low to high */

		if (context->count[0] < copy_size)

			context->count[1]++;

		if ((context->count[0] & 0x3F) == 0)

			transform(context->state, context->buffer.u32);

	}

}

void fz_sha256_final(fz_sha256 *context, unsigned char digest[32])

{

	/* Add padding as described in RFC 3174 (it describes SHA-1 but

	 * the same padding style is used for SHA-256 too). */

	unsigned int j = context->count[0] & 0x3F;

	context->buffer.u8[j++] = 0x80;

	while (j != 56)

	{

		if (j == 64)

		{

			transform(context->state, context->buffer.u32);

			j = 0;

		}

		context->buffer.u8[j++] = 0x00;

	}

	/* Convert the message size from bytes to bits. */

	context->count[1] = (context->count[1] << 3) + (context->count[0] >> 29);

	context->count[0] = context->count[0] << 3;

	context->buffer.u32[14] = bswap32(context->count[1]);

	context->buffer.u32[15] = bswap32(context->count[0]);

	transform(context->state, context->buffer.u32);

	for (j = 0; j < 8; j++)

		((unsigned int *)digest)[j] = bswap32(context->state[j]);

	memset(context, 0, sizeof(fz_sha256));

}