Changeset a0f2b6 in git

Timestamp:

Aug 30, 2018, 11:00:33 AM (5 years ago)

Author:

Karim Abou Zeid <karim23697@…>

Branches:

(u'spielwiese', 'a719bcf0b8dbc648b128303a49777a094b57592c')

Children:

72436190c57e0fc29bf8613364fedc842ab8f950

Parents:

220277fa8e83a4114de1b10f16c45589bf2e4730

Message:

Make prepend more efficient in letterplace kernel multiplication

File:

• libpolys/polys/shiftop.cc (modified) (4 diffs)

libpolys/polys/shiftop.cc

@@ -344 +344 @@
 }
 
-// appends m2ExpV to m1ExpV where m1Last is the last Vblock of m1 and m2Last the last Vblock of m2
-// also adds their components (one of them is always zero)
+// appends m2ExpV to m1ExpV, also adds their components (one of them is always zero)
 void p_LPExpVappend(int *m1ExpV, int *m2ExpV, int m1Length, int m2Length, const ring ri) {
 #ifdef SHIFT_MULT_DEBUG
@@ -366 +365 @@
 }
 
-// prepends m2ExpV to m1ExpV where m1Last is the last Vblock of m1 and m2Last the last Vblock of m2
-// also adds their components (one of them is always zero)
+// prepends m2ExpV to m1ExpV, also adds their components (one of them is always zero)
 void p_LPExpVprepend(int *m1ExpV, int *m2ExpV, int m1Length, int m2Length, const ring ri) {
 #ifdef SHIFT_MULT_DEBUG
@@ -376 +374 @@
   assume(m1Length + m2Length <= ri->N);
 
-  // save m1
-  int *m1Tmp=(int *)omAlloc0((m1Length+1)*sizeof(int));
-  for (int i = 1; i < 1 + m1Length; ++i) {
-    m1Tmp[i] = m1ExpV[i];
+  // shift m1 by m2Length
+  for (int i = m2Length + m1Length; i >= 1 + m2Length; --i)
+  {
+    m1ExpV[i] = m1ExpV[i - m2Length];
   }
 
@@ -388 +386 @@
     m1ExpV[i] = m2ExpV[i];
   }
-  // then append m1 again
-  for (int i = 1 + m2Length; i < 1 + m2Length + m1Length; ++i) {
-    m1ExpV[i] = m1Tmp[i - m2Length];
-  }
-  omFreeSize((ADDRESS) m1Tmp, (m1Length+1)*sizeof(int));
 
   assume(m1ExpV[0] == 0 || m2ExpV[0] == 0); // one component should be zero (otherwise this doesn't make any sense)