/* $OpenBSD: md32_common.h,v 1.22 2016/11/04 13:56:04 miod Exp $ */
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
 * 1. Redistributions of source code must retain the above copyright
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 *    distribution.
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 * 3. All advertising materials mentioning features or use of this
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 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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 * 5. Products derived from this software may not be called "OpenSSL"
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 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
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/*
 * This is a generic 32 bit "collector" for message digest algorithms.
 * Whenever needed it collects input character stream into chunks of
 * 32 bit values and invokes a block function that performs actual hash
 * calculations.
 *
 * Porting guide.
 *
 * Obligatory macros:
 *
 * DATA_ORDER_IS_BIG_ENDIAN or DATA_ORDER_IS_LITTLE_ENDIAN
 *      this macro defines byte order of input stream.
 * HASH_CBLOCK
 *      size of a unit chunk HASH_BLOCK operates on.
 * HASH_LONG
 *      has to be at least 32 bit wide.
 * HASH_CTX
 *      context structure that at least contains following
 *      members:
 *              typedef struct {
 *                      ...
 *                      HASH_LONG       Nl,Nh;
 *                      either {
 *                      HASH_LONG       data[HASH_LBLOCK];
 *                      unsigned char   data[HASH_CBLOCK];
 *                      };
 *                      unsigned int    num;
 *                      ...
 *                      } HASH_CTX;
 *      data[] vector is expected to be zeroed upon first call to
 *      HASH_UPDATE.
 * HASH_UPDATE
 *      name of "Update" function, implemented here.
 * HASH_TRANSFORM
 *      name of "Transform" function, implemented here.
 * HASH_FINAL
 *      name of "Final" function, implemented here.
 * HASH_BLOCK_DATA_ORDER
 *      name of "block" function capable of treating *unaligned* input
 *      message in original (data) byte order, implemented externally.
 * HASH_MAKE_STRING
 *      macro convering context variables to an ASCII hash string.
 *
 * MD5 example:
 *
 *      #define DATA_ORDER_IS_LITTLE_ENDIAN
 *
 *      #define HASH_LONG               MD5_LONG
 *      #define HASH_CTX                MD5_CTX
 *      #define HASH_CBLOCK             MD5_CBLOCK
 *      #define HASH_UPDATE             MD5_Update
 *      #define HASH_TRANSFORM          MD5_Transform
 *      #define HASH_FINAL              MD5_Final
 *      #define HASH_BLOCK_DATA_ORDER   md5_block_data_order
 *
 *                                      <appro@fy.chalmers.se>
 */

#include <stdint.h>

#include <openssl/opensslconf.h>

#if !defined(DATA_ORDER_IS_BIG_ENDIAN) && !defined(DATA_ORDER_IS_LITTLE_ENDIAN)
#error "DATA_ORDER must be defined!"
#endif

#ifndef HASH_CBLOCK
#error "HASH_CBLOCK must be defined!"
#endif
#ifndef HASH_LONG
#error "HASH_LONG must be defined!"
#endif
#ifndef HASH_CTX
#error "HASH_CTX must be defined!"
#endif

#ifndef HASH_UPDATE
#error "HASH_UPDATE must be defined!"
#endif
#ifndef HASH_TRANSFORM
#error "HASH_TRANSFORM must be defined!"
#endif
#if !defined(HASH_FINAL) && !defined(HASH_NO_FINAL)
#error "HASH_FINAL or HASH_NO_FINAL must be defined!"
#endif

#ifndef HASH_BLOCK_DATA_ORDER
#error "HASH_BLOCK_DATA_ORDER must be defined!"
#endif

/*
 * This common idiom is recognized by the compiler and turned into a
 * CPU-specific intrinsic as appropriate. 
 * e.g. GCC optimizes to roll on amd64 at -O0
 */
static inline uint32_t ROTATE(uint32_t a, uint32_t n)
{
        return (a<<n)|(a>>(32-n));
}

#if defined(DATA_ORDER_IS_BIG_ENDIAN)

#if defined(__GNUC__) && __GNUC__>=2 && !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM)
# if (defined(__i386) || defined(__i386__) || \
      defined(__x86_64) || defined(__x86_64__))
    /*
     * This gives ~30-40% performance improvement in SHA-256 compiled
     * with gcc [on P4]. Well, first macro to be frank. We can pull
     * this trick on x86* platforms only, because these CPUs can fetch
     * unaligned data without raising an exception.
     */
#  define HOST_c2l(c,l) ({ unsigned int r=*((const unsigned int *)(c)); \
                                   asm ("bswapl %0":"=r"(r):"0"(r));    \
                                   (c)+=4; (l)=r;                       })
#  define HOST_l2c(l,c) ({ unsigned int r=(l);                  \
                                   asm ("bswapl %0":"=r"(r):"0"(r));    \
                                   *((unsigned int *)(c))=r; (c)+=4;    })
# endif
#endif

#ifndef HOST_c2l
#define HOST_c2l(c,l) do {l =(((unsigned long)(*((c)++)))<<24); \
                          l|=(((unsigned long)(*((c)++)))<<16); \
                          l|=(((unsigned long)(*((c)++)))<< 8); \
                          l|=(((unsigned long)(*((c)++)))    ); \
                      } while (0)
#endif
#ifndef HOST_l2c
#define HOST_l2c(l,c) do {*((c)++)=(unsigned char)(((l)>>24)&0xff);     \
                          *((c)++)=(unsigned char)(((l)>>16)&0xff);     \
                          *((c)++)=(unsigned char)(((l)>> 8)&0xff);     \
                          *((c)++)=(unsigned char)(((l)    )&0xff);     \
                      } while (0)
#endif

#elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)

#if defined(__i386) || defined(__i386__) || defined(__x86_64) || defined(__x86_64__)
#  define HOST_c2l(c,l) ((l)=*((const unsigned int *)(c)), (c)+=4)
#  define HOST_l2c(l,c) (*((unsigned int *)(c))=(l), (c)+=4)
#endif

#ifndef HOST_c2l
#define HOST_c2l(c,l) do {l =(((unsigned long)(*((c)++)))    ); \
                          l|=(((unsigned long)(*((c)++)))<< 8); \
                          l|=(((unsigned long)(*((c)++)))<<16); \
                          l|=(((unsigned long)(*((c)++)))<<24); \
                      } while (0)
#endif
#ifndef HOST_l2c
#define HOST_l2c(l,c) do {*((c)++)=(unsigned char)(((l)    )&0xff);     \
                          *((c)++)=(unsigned char)(((l)>> 8)&0xff);     \
                          *((c)++)=(unsigned char)(((l)>>16)&0xff);     \
                          *((c)++)=(unsigned char)(((l)>>24)&0xff);     \
                      } while (0)
#endif

#endif

/*
 * Time for some action:-)
 */

int
HASH_UPDATE(HASH_CTX *c, const void *data_, size_t len)
{
        const unsigned char *data = data_;
        unsigned char *p;
        HASH_LONG l;
        size_t n;

        if (len == 0)
                return 1;

        l = (c->Nl + (((HASH_LONG)len) << 3))&0xffffffffUL;
        /* 95-05-24 eay Fixed a bug with the overflow handling, thanks to
         * Wei Dai <weidai@eskimo.com> for pointing it out. */
        if (l < c->Nl) /* overflow */
                c->Nh++;
        c->Nh+=(HASH_LONG)(len>>29);    /* might cause compiler warning on 16-bit */
        c->Nl = l;

        n = c->num;
        if (n != 0) {
                p = (unsigned char *)c->data;

                if (len >= HASH_CBLOCK || len + n >= HASH_CBLOCK) {
                        memcpy (p + n, data, HASH_CBLOCK - n);
                        HASH_BLOCK_DATA_ORDER (c, p, 1);
                        n = HASH_CBLOCK - n;
                        data += n;
                        len -= n;
                        c->num = 0;
                        memset (p,0,HASH_CBLOCK);       /* keep it zeroed */
                } else {
                        memcpy (p + n, data, len);
                        c->num += (unsigned int)len;
                        return 1;
                }
        }

        n = len/HASH_CBLOCK;
        if (n > 0) {
                HASH_BLOCK_DATA_ORDER (c, data, n);
                n    *= HASH_CBLOCK;
                data += n;
                len -= n;
        }

        if (len != 0) {
                p = (unsigned char *)c->data;
                c->num = (unsigned int)len;
                memcpy (p, data, len);
        }
        return 1;
}


void HASH_TRANSFORM (HASH_CTX *c, const unsigned char *data)
{
        HASH_BLOCK_DATA_ORDER (c, data, 1);
}


#ifndef HASH_NO_FINAL
int HASH_FINAL (unsigned char *md, HASH_CTX *c)
{
        unsigned char *p = (unsigned char *)c->data;
        size_t n = c->num;

        p[n] = 0x80; /* there is always room for one */
        n++;

        if (n > (HASH_CBLOCK - 8)) {
                memset (p + n, 0, HASH_CBLOCK - n);
                n = 0;
                HASH_BLOCK_DATA_ORDER (c, p, 1);
        }
        memset (p + n, 0, HASH_CBLOCK - 8 - n);

        p += HASH_CBLOCK - 8;
#if   defined(DATA_ORDER_IS_BIG_ENDIAN)
        HOST_l2c(c->Nh, p);
        HOST_l2c(c->Nl, p);
#elif defined(DATA_ORDER_IS_LITTLE_ENDIAN)
        HOST_l2c(c->Nl, p);
        HOST_l2c(c->Nh, p);
#endif
        p -= HASH_CBLOCK;
        HASH_BLOCK_DATA_ORDER (c, p, 1);
        c->num = 0;
        memset (p, 0, HASH_CBLOCK);

#ifndef HASH_MAKE_STRING
#error "HASH_MAKE_STRING must be defined!"
#else
        HASH_MAKE_STRING(c, md);
#endif

        return 1;
}
#endif

#ifndef MD32_REG_T
#if defined(__alpha) || defined(__sparcv9) || defined(__mips)
#define MD32_REG_T long
/*
 * This comment was originaly written for MD5, which is why it
 * discusses A-D. But it basically applies to all 32-bit digests,
 * which is why it was moved to common header file.
 *
 * In case you wonder why A-D are declared as long and not
 * as MD5_LONG. Doing so results in slight performance
 * boost on LP64 architectures. The catch is we don't
 * really care if 32 MSBs of a 64-bit register get polluted
 * with eventual overflows as we *save* only 32 LSBs in
 * *either* case. Now declaring 'em long excuses the compiler
 * from keeping 32 MSBs zeroed resulting in 13% performance
 * improvement under SPARC Solaris7/64 and 5% under AlphaLinux.
 * Well, to be honest it should say that this *prevents*
 * performance degradation.
 *                              <appro@fy.chalmers.se>
 */
#else
/*
 * Above is not absolute and there are LP64 compilers that
 * generate better code if MD32_REG_T is defined int. The above
 * pre-processor condition reflects the circumstances under which
 * the conclusion was made and is subject to further extension.
 *                              <appro@fy.chalmers.se>
 */
#define MD32_REG_T int
#endif
#endif