The Tor Browser: security/nss/lib/freebl/mpi/mpvalpha.c@b8a032363ba2

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #include "mpi-priv.h"

     6 #include <c_asm.h>

     9 #define MP_MUL_DxD(a, b, Phi, Plo)		\

    10  { Plo = asm ("mulq %a0, %a1, %v0", a, b);	\

    11    Phi = asm ("umulh %a0, %a1, %v0", a, b); }	\

    13 /* This is empty for the loop in s_mpv_mul_d	*/

    14 #define CARRY_ADD

    16 #define ONE_MUL				\

    17     a_i = *a++;				\

    18     MP_MUL_DxD(a_i, b, a1b1, a0b0);	\

    19     a0b0 += carry;			\

    20     if (a0b0 < carry)			\

    21       ++a1b1;				\

    22     CARRY_ADD				\

    23     *c++ = a0b0;			\

    24     carry = a1b1;			\

    26 #define FOUR_MUL			\

    27 	ONE_MUL				\

    28 	ONE_MUL				\

    29 	ONE_MUL				\

    30 	ONE_MUL				\

    32 #define SIXTEEN_MUL			\

    33 	FOUR_MUL			\

    34 	FOUR_MUL			\

    35 	FOUR_MUL			\

    36 	FOUR_MUL			\

    38 #define THIRTYTWO_MUL			\

    39 	SIXTEEN_MUL			\

    40 	SIXTEEN_MUL			\

    42 #define ONETWENTYEIGHT_MUL		\

    43 	THIRTYTWO_MUL			\

    44 	THIRTYTWO_MUL			\

    45 	THIRTYTWO_MUL			\

    46 	THIRTYTWO_MUL			\

    49 #define EXPAND_256(CALL)		\

    50  mp_digit carry = 0;			\

    51  mp_digit a_i;				\

    52  mp_digit a0b0, a1b1;			\

    53  if (a_len &255) {			\

    54 	if (a_len &1) {			\

    55 	  ONE_MUL			\

    56 	}				\

    57 	if (a_len &2) {			\

    58 	  ONE_MUL			\

    59 	  ONE_MUL			\

    60 	}				\

    61 	if (a_len &4) {			\

    62 	  FOUR_MUL			\

    63 	}				\

    64 	if (a_len &8) {			\

    65 	  FOUR_MUL			\

    66 	  FOUR_MUL			\

    67 	}				\

    68 	if (a_len & 16 ) {		\

    69 	  SIXTEEN_MUL			\

    70 	}				\

    71 	if (a_len & 32 ) {		\

    72 	  THIRTYTWO_MUL			\

    73 	}				\

    74 	if (a_len & 64 ) {		\

    75 	  THIRTYTWO_MUL			\

    76 	  THIRTYTWO_MUL			\

    77 	}				\

    78 	if (a_len & 128) {		\

    79 	  ONETWENTYEIGHT_MUL		\

    80 	}				\

    81 	a_len = a_len & (-256);		\

    82   }					\

    83   if (a_len>=256 ) {			\

    84 	carry = CALL(a, a_len, b, c, carry);	\

    85 	c += a_len;			\

    86   }					\

    88 #define FUNC_NAME(NAME)			\

    89 mp_digit NAME(const mp_digit *a, 	\

    90 	mp_size a_len,			\

    91 	mp_digit b, mp_digit *c, 	\

    92 	mp_digit carry)			\

    94 #define DECLARE_MUL_256(FNAME)		\

    95 FUNC_NAME(FNAME)			\

    96 {					\

    97   mp_digit a_i;				\

    98   mp_digit a0b0, a1b1;			\

    99   while (a_len) {			\

   100 	ONETWENTYEIGHT_MUL		\

   101 	ONETWENTYEIGHT_MUL		\

   102 	a_len-= 256;			\

   103   }					\

   104   return carry;				\

   105 }					\

   107 /* Expanding the loop in s_mpv_mul_d appeared to slow down the

   108    (admittedly) small number of tests (i.e., timetest) used to

   109    measure performance, so this define disables that optimization. */

   110 #define DO_NOT_EXPAND 1

   112 /* Need forward declaration so it can be instantiated after

   113 	the routine that uses it; this helps locality somewhat	*/

   114 #if !defined(DO_NOT_EXPAND)

   115 FUNC_NAME(s_mpv_mul_d_MUL256);

   116 #endif

   118 /* c = a * b */

   119 void s_mpv_mul_d(const mp_digit *a, mp_size a_len,

   120 			mp_digit b, mp_digit *c)

   121 {

   122 #if defined(DO_NOT_EXPAND)

   123   mp_digit carry = 0;

   124   while (a_len--) {

   125     mp_digit a_i = *a++;

   126     mp_digit a0b0, a1b1;

   128     MP_MUL_DxD(a_i, b, a1b1, a0b0);

   130     a0b0 += carry;

   131     if (a0b0 < carry)

   132       ++a1b1;

   133     *c++ = a0b0;

   134     carry = a1b1;

   135   }

   136 #else

   137   EXPAND_256(s_mpv_mul_d_MUL256)

   138 #endif

   139   *c = carry;

   140 }

   142 #if !defined(DO_NOT_EXPAND)

   143 DECLARE_MUL_256(s_mpv_mul_d_MUL256)

   144 #endif

   146 #undef CARRY_ADD

   147 /* This is redefined for the loop in s_mpv_mul_d_add */

   148 #define CARRY_ADD			\

   149     a0b0 += a_i = *c;			\

   150     if (a0b0 < a_i)			\

   151       ++a1b1;				\

   153 /* Need forward declaration so it can be instantiated between the

   154 	two routines that use it; this helps locality somewhat	*/

   155 FUNC_NAME(s_mpv_mul_d_add_MUL256);

   157 /* c += a * b */

   158 void s_mpv_mul_d_add(const mp_digit *a, mp_size a_len,

   159 			mp_digit b, mp_digit *c)

   160 {

   161   EXPAND_256(s_mpv_mul_d_add_MUL256)

   162   *c = carry;

   163 }

   165 /* Instantiate multiply 256 routine here */

   166 DECLARE_MUL_256(s_mpv_mul_d_add_MUL256)

   168 /* Presently, this is only used by the Montgomery arithmetic code. */

   169 /* c += a * b */

   170 void s_mpv_mul_d_add_prop(const mp_digit *a, mp_size a_len,

   171 			mp_digit b, mp_digit *c)

   172 {

   173   EXPAND_256(s_mpv_mul_d_add_MUL256)

   174   while (carry) {

   175     mp_digit c_i = *c;

   176     carry += c_i;

   177     *c++ = carry;

   178     carry = carry < c_i;

   179   }

   180 }

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