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simplifications: mul/sqr comba

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This commit is contained in:
Daniel Mendler 2019-10-29 20:06:20 +01:00
parent 7b6c6965bb
commit 8ac493512c
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GPG Key ID: D88ADB2A2693CA43
5 changed files with 50 additions and 102 deletions
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29
s_mp_mul_digs.c
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@ -11,10 +11,7 @@ mp_err s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
{
mp_int t;
mp_err err;
int pa, pb, ix, iy;
mp_digit u;
mp_word r;
mp_digit tmpx, *tmpt, *tmpy;
int pa, ix;
/* can we use the fast multiplier? */
if ((digs < MP_WARRAY) &&
@ -30,38 +27,28 @@ mp_err s_mp_mul_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
/* compute the digits of the product directly */
pa = a->used;
for (ix = 0; ix < pa; ix++) {
/* set the carry to zero */
u = 0;
int iy, pb;
mp_digit u = 0;
/* limit ourselves to making digs digits of output */
pb = MP_MIN(b->used, digs - ix);
/* setup some aliases */
/* copy of the digit from a used within the nested loop */
tmpx = a->dp[ix];
/* an alias for the destination shifted ix places */
tmpt = t.dp + ix;
/* an alias for the digits of b */
tmpy = b->dp;
/* compute the columns of the output and propagate the carry */
for (iy = 0; iy < pb; iy++) {
/* compute the column as a mp_word */
r = (mp_word)*tmpt +
((mp_word)tmpx * (mp_word)*tmpy++) +
(mp_word)u;
mp_word r = (mp_word)t.dp[ix + iy] +
((mp_word)a->dp[ix] * (mp_word)b->dp[iy]) +
(mp_word)u;
/* the new column is the lower part of the result */
*tmpt++ = (mp_digit)(r & (mp_word)MP_MASK);
t.dp[ix + iy] = (mp_digit)(r & (mp_word)MP_MASK);
/* get the carry word from the result */
u = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT);
}
/* set carry if it is placed below digs */
if ((ix + iy) < digs) {
*tmpt = u;
t.dp[ix + pb] = u;
}
}

32
s_mp_mul_digs_fast.c
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@ -21,7 +21,7 @@
*/
mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
{
int olduse, pa, ix, iz;
int oldused, pa, ix;
mp_err err;
mp_digit W[MP_WARRAY];
mp_word _W;
@ -39,18 +39,12 @@ mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
/* clear the carry */
_W = 0;
for (ix = 0; ix < pa; ix++) {
int tx, ty;
int iy;
mp_digit *tmpx, *tmpy;
int tx, ty, iy, iz;
/* get offsets into the two bignums */
ty = MP_MIN(b->used-1, ix);
tx = ix - ty;
/* setup temp aliases */
tmpx = a->dp + tx;
tmpy = b->dp + ty;
/* this is the number of times the loop will iterrate, essentially
while (tx++ < a->used && ty-- >= 0) { ... }
*/
@ -58,8 +52,7 @@ mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
/* execute loop */
for (iz = 0; iz < iy; ++iz) {
_W += (mp_word)*tmpx++ * (mp_word)*tmpy--;
_W += (mp_word)a->dp[tx + iz] * (mp_word)b->dp[ty - iz];
}
/* store term */
@ -70,20 +63,17 @@ mp_err s_mp_mul_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
}
/* setup dest */
olduse = c->used;
oldused = c->used;
c->used = pa;
{
mp_digit *tmpc;
tmpc = c->dp;
for (ix = 0; ix < pa; ix++) {
/* now extract the previous digit [below the carry] */
*tmpc++ = W[ix];
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(tmpc, olduse - ix);
for (ix = 0; ix < pa; ix++) {
/* now extract the previous digit [below the carry] */
c->dp[ix] = W[ix];
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(c->dp + c->used, oldused - c->used);
mp_clamp(c);
return MP_OKAY;
}

28
s_mp_mul_high_digs.c
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@ -9,11 +9,8 @@
mp_err s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
{
mp_int t;
int pa, pb, ix, iy;
int pa, pb, ix;
mp_err err;
mp_digit u;
mp_word r;
mp_digit tmpx, *tmpt, *tmpy;
/* can we use the fast multiplier? */
if (MP_HAS(S_MP_MUL_HIGH_DIGS_FAST)
@ -30,31 +27,22 @@ mp_err s_mp_mul_high_digs(const mp_int *a, const mp_int *b, mp_int *c, int digs)
pa = a->used;
pb = b->used;
for (ix = 0; ix < pa; ix++) {
/* clear the carry */
u = 0;
/* left hand side of A[ix] * B[iy] */
tmpx = a->dp[ix];
/* alias to the address of where the digits will be stored */
tmpt = &(t.dp[digs]);
/* alias for where to read the right hand side from */
tmpy = b->dp + (digs - ix);
int iy;
mp_digit u = 0;
for (iy = digs - ix; iy < pb; iy++) {
/* calculate the double precision result */
r = (mp_word)*tmpt +
((mp_word)tmpx * (mp_word)*tmpy++) +
(mp_word)u;
mp_word r = (mp_word)t.dp[ix + iy] +
((mp_word)a->dp[ix] * (mp_word)b->dp[iy]) +
(mp_word)u;
/* get the lower part */
*tmpt++ = (mp_digit)(r & (mp_word)MP_MASK);
t.dp[ix + iy] = (mp_digit)(r & (mp_word)MP_MASK);
/* carry the carry */
u = (mp_digit)(r >> (mp_word)MP_DIGIT_BIT);
}
*tmpt = u;
t.dp[ix + pb] = u;
}
mp_clamp(&t);
mp_exch(&t, c);

31
s_mp_mul_high_digs_fast.c
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@ -14,7 +14,7 @@
*/
mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int digs)
{
int olduse, pa, ix, iz;
int oldused, pa, ix;
mp_err err;
mp_digit W[MP_WARRAY];
mp_word _W;
@ -31,17 +31,12 @@ mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int
pa = a->used + b->used;
_W = 0;
for (ix = digs; ix < pa; ix++) {
int tx, ty, iy;
mp_digit *tmpx, *tmpy;
int tx, ty, iy, iz;
/* get offsets into the two bignums */
ty = MP_MIN(b->used-1, ix);
tx = ix - ty;
/* setup temp aliases */
tmpx = a->dp + tx;
tmpy = b->dp + ty;
/* this is the number of times the loop will iterrate, essentially its
while (tx++ < a->used && ty-- >= 0) { ... }
*/
@ -49,7 +44,7 @@ mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int
/* execute loop */
for (iz = 0; iz < iy; iz++) {
_W += (mp_word)*tmpx++ * (mp_word)*tmpy--;
_W += (mp_word)a->dp[tx + iz] * (mp_word)b->dp[ty - iz];
}
/* store term */
@ -60,21 +55,17 @@ mp_err s_mp_mul_high_digs_fast(const mp_int *a, const mp_int *b, mp_int *c, int
}
/* setup dest */
olduse = c->used;
oldused = c->used;
c->used = pa;
{
mp_digit *tmpc;
tmpc = c->dp + digs;
for (ix = digs; ix < pa; ix++) {
/* now extract the previous digit [below the carry] */
*tmpc++ = W[ix];
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(tmpc, olduse - ix);
for (ix = digs; ix < pa; ix++) {
/* now extract the previous digit [below the carry] */
c->dp[ix] = W[ix];
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(c->dp + c->used, oldused - c->used);
mp_clamp(c);
return MP_OKAY;
}

32
s_mp_sqr_fast.c
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@ -15,14 +15,14 @@ After that loop you do the squares and add them in.
mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
{
int olduse, pa, ix, iz;
mp_digit W[MP_WARRAY], *tmpx;
int oldused, pa, ix;
mp_digit W[MP_WARRAY];
mp_word W1;
mp_err err;
/* grow the destination as required */
pa = a->used + a->used;
if (b->alloc < pa) {
mp_err err;
if ((err = mp_grow(b, pa)) != MP_OKAY) {
return err;
}
@ -31,9 +31,8 @@ mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
/* number of output digits to produce */
W1 = 0;
for (ix = 0; ix < pa; ix++) {
int tx, ty, iy;
int tx, ty, iy, iz;
mp_word _W;
mp_digit *tmpy;
/* clear counter */
_W = 0;
@ -42,10 +41,6 @@ mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
ty = MP_MIN(a->used-1, ix);
tx = ix - ty;
/* setup temp aliases */
tmpx = a->dp + tx;
tmpy = a->dp + ty;
/* this is the number of times the loop will iterrate, essentially
while (tx++ < a->used && ty-- >= 0) { ... }
*/
@ -59,7 +54,7 @@ mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
/* execute loop */
for (iz = 0; iz < iy; iz++) {
_W += (mp_word)*tmpx++ * (mp_word)*tmpy--;
_W += (mp_word)a->dp[tx + iz] * (mp_word)a->dp[ty - iz];
}
/* double the inner product and add carry */
@ -78,19 +73,16 @@ mp_err s_mp_sqr_fast(const mp_int *a, mp_int *b)
}
/* setup dest */
olduse = b->used;
oldused = b->used;
b->used = a->used+a->used;
{
mp_digit *tmpb;
tmpb = b->dp;
for (ix = 0; ix < pa; ix++) {
*tmpb++ = W[ix] & MP_MASK;
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(tmpb, olduse - ix);
for (ix = 0; ix < pa; ix++) {
b->dp[ix] = W[ix] & MP_MASK;
}
/* clear unused digits [that existed in the old copy of c] */
MP_ZERO_DIGITS(b->dp + b->used, oldused - b->used);
mp_clamp(b);
return MP_OKAY;
}