mp-gcd, gf-gcd: Tweak memory management subtly.

Avoid mp churn by keeping a single spare integer lying around during the
main loop.

diff --git a/gf-gcd.c b/gf-gcd.c
index 9b5402b..03cee47 100644 (file)
--- a/gf-gcd.c
+++ b/gf-gcd.c
@@ -51,7 +51,7 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
   mp *x = MP_ONE, *X = MP_ZERO;
   mp *y = MP_ZERO, *Y = MP_ONE;
   mp *u, *v;
   mp *x = MP_ONE, *X = MP_ZERO;
   mp *y = MP_ZERO, *Y = MP_ONE;
   mp *u, *v;

-  mp *q = MP_NEW;
+  mp *q = MP_NEW, *t, *spare = MP_NEW;

   unsigned f = 0;
 
 #define f_swap 1u
   unsigned f = 0;
 
 #define f_swap 1u


@@ -69,7 +69,7 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
    */
 
   if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {
    */
 
   if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {

-    { mp *t = a; a = b; b = t; }
+    t = a; a = b; b = t;

     f |= f_swap;
   }
 
     f |= f_swap;
   }
 


@@ -112,20 +112,19 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
   v = MP_COPY(b);
 
   while (!MP_ZEROP(v)) {
   v = MP_COPY(b);
 
   while (!MP_ZEROP(v)) {

-    mp *t;

     gf_div(&q, &u, u, v);
     if (f & f_ext) {
     gf_div(&q, &u, u, v);
     if (f & f_ext) {

-      t = gf_mul(MP_NEW, X, q);
+      t = gf_mul(spare, X, q);

       t = gf_add(t, t, x);
       t = gf_add(t, t, x);

-      MP_DROP(x); x = X; X = t;
-      t = gf_mul(MP_NEW, Y, q);
+      spare = x; x = X; X = t;
+      t = gf_mul(spare, Y, q);

       t = gf_add(t, t, y);
       t = gf_add(t, t, y);

-      MP_DROP(y); y = Y; Y = t;
+      spare = y; y = Y; Y = t;

     }
     t = u; u = v; v = t;
   }
 
     }
     t = u; u = v; v = t;
   }
 

-  MP_DROP(q);
+  MP_DROP(q); if (spare) MP_DROP(spare);

   if (!gcd)
     MP_DROP(u);
   else {
   if (!gcd)
     MP_DROP(u);
   else {


@@ -141,7 +140,7 @@ void gf_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
     /* --- If @a@ and @b@ got swapped, swap the coefficients back --- */
 
     if (f & f_swap) {
     /* --- If @a@ and @b@ got swapped, swap the coefficients back --- */
 
     if (f & f_swap) {

-      mp *t = x; x = y; y = t;
+      t = x; x = y; y = t;

       t = a; a = b; b = t;
     }
 
       t = a; a = b; b = t;
     }
 

diff --git a/mp-gcd.c b/mp-gcd.c
index 2583c8e..40531c7 100644 (file)
--- a/mp-gcd.c
+++ b/mp-gcd.c
@@ -50,7 +50,7 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
   mp *x = MP_ONE, *X = MP_ZERO;
   mp *y = MP_ZERO, *Y = MP_ONE;
   mp *u, *v;
   mp *x = MP_ONE, *X = MP_ZERO;
   mp *y = MP_ZERO, *Y = MP_ONE;
   mp *u, *v;

-  mp *q = MP_NEW;
+  mp *q = MP_NEW, *t, *spare = MP_NEW;

   unsigned f = 0;
 
 #define f_swap 1u
   unsigned f = 0;
 
 #define f_swap 1u


@@ -74,13 +74,13 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
    */
 
   if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {
    */
 
   if (MPX_UCMP(a->v, a->vl, <, b->v, b->vl)) {

-    { mp *t = a; a = b; b = t; }
+    t = a; a = b; b = t;

     f |= f_swap;
   }
 
   /* --- Check for zeroness --- */
 
     f |= f_swap;
   }
 
   /* --- Check for zeroness --- */
 

-  if (MP_EQ(b, MP_ZERO)) {
+  if (MP_ZEROP(b)) {

 
     /* --- Store %$|a|$% as the GCD --- */
 
 
     /* --- Store %$|a|$% as the GCD --- */
 


@@ -99,7 +99,7 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
 
     if (f & f_ext) {
       if (f & f_swap) {
 
     if (f & f_ext) {
       if (f & f_swap) {

-       mp **t = xx; xx = yy; yy = t;
+       mp **tt = xx; xx = yy; yy = tt;

       }
       if (xx) {
        if (*xx) MP_DROP(*xx);
       }
       if (xx) {
        if (*xx) MP_DROP(*xx);


@@ -132,20 +132,19 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
   /* --- Main extended Euclidean algorithm --- */
 
   while (!MP_ZEROP(v)) {
   /* --- Main extended Euclidean algorithm --- */
 
   while (!MP_ZEROP(v)) {

-    mp *t;

     mp_div(&q, &u, u, v);
     if (f & f_ext) {
     mp_div(&q, &u, u, v);
     if (f & f_ext) {

-      t = mp_mul(MP_NEW, X, q);
+      t = mp_mul(spare, X, q);

       t = mp_sub(t, x, t);
       t = mp_sub(t, x, t);

-      MP_DROP(x); x = X; X = t;
-      t = mp_mul(MP_NEW, Y, q);
+      spare = x; x = X; X = t;
+      t = mp_mul(spare, Y, q);

       t = mp_sub(t, y, t);
       t = mp_sub(t, y, t);

-      MP_DROP(y); y = Y; Y = t;
+      spare = y; y = Y; Y = t;

     }
     t = u; u = v; v = t;
   }
 
     }
     t = u; u = v; v = t;
   }
 

-  MP_DROP(q);
+  MP_DROP(q); if (spare) MP_DROP(spare);

   if (!gcd)
     MP_DROP(u);
   else {
   if (!gcd)
     MP_DROP(u);
   else {


@@ -166,7 +165,7 @@ void mp_gcd(mp **gcd, mp **xx, mp **yy, mp *a, mp *b)
     /* --- If @a@ and @b@ got swapped, swap the coefficients back --- */
 
     if (f & f_swap) {
     /* --- If @a@ and @b@ got swapped, swap the coefficients back --- */
 
     if (f & f_swap) {

-      mp *t = x; x = y; y = t;
+      t = x; x = y; y = t;

       t = a; a = b; b = t;
     }
 
       t = a; a = b; b = t;
     }