X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/dd22938ef0d9b0131dad9171a8a95866ceec9607..1589affab225db500965e2cb869c534d6860e6bd:/mp-arith.c

diff --git a/mp-arith.c b/mp-arith.c
index 23137e2..53584e7 100644
--- a/mp-arith.c
+++ b/mp-arith.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: mp-arith.c,v 1.12 2002/10/09 00:36:03 mdw Exp $
+ * $Id: mp-arith.c,v 1.17 2003/10/12 15:03:35 mdw Exp $
  *
  * Basic arithmetic on multiprecision integers
  *
@@ -30,6 +30,24 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: mp-arith.c,v $
+ * Revision 1.17  2003/10/12 15:03:35  mdw
+ * Merge fix from other branch.
+ *
+ * Revision 1.16.2.1  2003/06/10 13:21:10  mdw
+ * Fix bug dividing small things by large ones.
+ *
+ * Revision 1.16  2003/05/16 09:09:24  mdw
+ * Fix @mp_lsl2c@.  Turns out to be surprisingly tricky.
+ *
+ * Revision 1.15  2002/10/19 17:56:50  mdw
+ * Fix bit operations.  Test them (a bit) better.
+ *
+ * Revision 1.14  2002/10/15 19:18:31  mdw
+ * New operation to negate numbers.
+ *
+ * Revision 1.13  2002/10/15 00:19:40  mdw
+ * Bit setting and clearing functions.
+ *
  * Revision 1.12  2002/10/09 00:36:03  mdw
  * Fix bounds on workspace for Karatsuba operations.
  *
@@ -82,13 +100,18 @@
 
 /*----- Main code ---------------------------------------------------------*/
 
-/* --- @mp_lsl@, @mp_lsr@ --- *
+/* --- @mp_lsl@, @mp_lslc@, @mp_lsr@ --- *
  *
  * Arguments:	@mp *d@ = destination
  *		@mp *a@ = source
  *		@size_t n@ = number of bits to move
  *
  * Returns:	Result, @a@ shifted left or right by @n@.
+ *
+ * Use:		Bitwise shift operators.  @mp_lslc@ fills the bits introduced
+ *		on the right with ones instead of zeroes: it's used
+ *		internally by @mp_lsl2c@, though it may be useful on its
+ *		own.
  */
 
 mp *mp_lsl(mp *d, mp *a, size_t n)
@@ -100,6 +123,15 @@ mp *mp_lsl(mp *d, mp *a, size_t n)
   return (d);
 }
 
+mp *mp_lslc(mp *d, mp *a, size_t n)
+{
+  MP_DEST(d, MP_LEN(a) + (n + MPW_BITS - 1) / MPW_BITS, a->f);
+  mpx_lslc(d->v, d->vl, a->v, a->vl, n);
+  d->f = a->f & (MP_NEG | MP_BURN);
+  MP_SHRINK(d);
+  return (d);
+}
+
 mp *mp_lsr(mp *d, mp *a, size_t n)
 {
   MP_DEST(d, MP_LEN(a), a->f);
@@ -124,7 +156,7 @@ mp *mp_lsl2c(mp *d, mp *a, size_t n)
   if (!(a->f & MP_NEG))
     return (mp_lsl(d, a, n));
   d = mp_not2c(d, a);
-  d = mp_lsl(d, d, n);
+  d = mp_lslc(d, d, n);
   d = mp_not2c(d, d);
   return (d);
 }
@@ -142,34 +174,31 @@ mp *mp_lsr2c(mp *d, mp *a, size_t n)
 /* --- @mp_testbit@ --- *
  *
  * Arguments:	@mp *x@ = a large integer
- *		@size_t n@ = which bit to test
+ *		@unsigned long n@ = which bit to test
  *
  * Returns:	Nonzero if the bit is set, zero if not.
  */
 
-int mp_testbit(mp *x, size_t n)
+int mp_testbit(mp *x, unsigned long n)
 {
-  size_t o;
   if (n > MPW_BITS * MP_LEN(x))
     return (0);
-  o = n / MPW_BITS;
-  n %= MPW_BITS;
-  return ((x->v[o] >> n) & 1);
+  return ((x->v[n/MPW_BITS] >> n%MPW_BITS) & 1u);
 }
 
 /* --- @mp_testbit2c@ --- *
  *
  * Arguments:	@mp *x@ = a large integer
- *		@size_t n@ = which bit to test
+ *		@unsigned long n@ = which bit to test
  *
  * Returns:	Nonzero if the bit is set, zero if not.  Fakes up two's
  *		complement representation.
  */
 
-int mp_testbit2c(mp *x, size_t n)
+int mp_testbit2c(mp *x, unsigned long n)
 {
   int r;
-  if (x->f & MP_NEG)
+  if (!(x->f & MP_NEG))
     return (mp_testbit(x, n));
   x = mp_not2c(MP_NEW, x);
   r = !mp_testbit(x, n);
@@ -177,6 +206,73 @@ int mp_testbit2c(mp *x, size_t n)
   return (r);
 }
 
+/* --- @mp_setbit@, @mp_clearbit@ --- *
+ *
+ * Arguments:	@mp *d@ = a destination
+ *		@mp *x@ = a large integer
+ *		@unsigned long n@ = which bit to modify
+ *
+ * Returns:	The argument @x@, with the appropriate bit set or cleared.
+ */
+
+mp *mp_setbit(mp *d, mp *x, unsigned long n)
+{
+  size_t rq;
+
+  rq = n + MPW_BITS; rq -= rq % MPW_BITS;
+  if (d != x) {
+    if (d) MP_DROP(d);
+    d = MP_COPY(x);
+  }
+  MP_DEST(d, rq, x->f & (MP_NEG | MP_BURN));
+  d->v[n/MPW_BITS] |= 1 << n%MPW_BITS;
+  return (d);
+}
+
+mp *mp_clearbit(mp *d, mp *x, unsigned long n)
+{
+  size_t rq;
+
+  rq = n + MPW_BITS; rq -= rq % MPW_BITS;
+  if (d != x) {
+    if (d) MP_DROP(d);
+    d = MP_COPY(x);
+  }
+  MP_DEST(d, rq, x->f & (MP_NEG | MP_BURN));
+  d->v[n/MPW_BITS] &= ~(1 << n%MPW_BITS);
+  return (d);
+}
+
+/* --- @mp_setbit2c@, @mp_clearbit2c@ --- *
+ *
+ * Arguments:	@mp *d@ = a destination
+ *		@mp *x@ = a large integer
+ *		@unsigned long n@ = which bit to modify
+ *
+ * Returns:	The argument @x@, with the appropriate bit set or cleared.
+ *		Fakes up two's complement representation.
+ */
+
+mp *mp_setbit2c(mp *d, mp *x, unsigned long n)
+{
+  if (!(x->f & MP_NEG))
+    return mp_setbit(d, x, n);
+  d = mp_not2c(d, x);
+  d = mp_clearbit(d, d, n);
+  d = mp_not2c(d, d);
+  return (d);
+}
+
+mp *mp_clearbit2c(mp *d, mp *x, unsigned long n)
+{
+  if (!(x->f & MP_NEG))
+    return mp_clearbit(d, x, n);
+  d = mp_not2c(d, x);
+  d = mp_setbit(d, d, n);
+  d = mp_not2c(d, d);
+  return (d);
+}
+
 /* --- @mp_eq@ --- *
  *
  * Arguments:	@const mp *a, *b@ = two numbers
@@ -204,6 +300,31 @@ int mp_cmp(const mp *a, const mp *b)
     return (+1);
 }
 
+/* --- @mp_neg@ --- *
+ *
+ * Arguments:	@mp *d@ = destination
+ *		@mp *a@ = argument
+ *
+ * Returns:	The negation of the argument.
+ *
+ * Use:		Negates its argument.
+ */
+
+mp *mp_neg(mp *d, mp *a)
+{
+  /* --- Surprising amounts of messing about required --- */
+
+  MP_SHRINK(a);
+  MP_COPY(a);
+  if (d)
+    MP_DROP(d);
+  if (a->v == a->vl)
+    return (a);
+  MP_DEST(a, MP_LEN(a), a->f);
+  a->f ^= MP_NEG;
+  return (a);
+}
+
 /* --- @mp_bitop@ --- *
  *
  * Arguments:	@mp *d@ = destination
@@ -223,7 +344,7 @@ int mp_cmp(const mp *a, const mp *b)
 									\
 mp *mp_bit##string(mp *d, mp *a, mp *b)					\
 {									\
-  MP_DEST(d, MAX(MP_LEN(a), MP_LEN(b)), a->f | b->f);			\
+  MP_DEST(d, MAX(MP_LEN(a), MP_LEN(b)), (a->f | b->f) & ~MP_NEG);	\
   mpx_bit##string(d->v, d->vl, a->v, a->vl, b->v, b->vl);		\
   d->f = (a->f | b->f) & MP_BURN;					\
   MP_SHRINK(d);								\
@@ -504,7 +625,7 @@ void mp_div(mp **qq, mp **rr, mp *a, mp *b)
   if (r)
     MP_DROP(r);
   r = a;
-  MP_DEST(r, MP_LEN(a) + 2, a->f | b->f);
+  MP_DEST(r, MAX(MP_LEN(a), MP_LEN(b)) + 2, a->f | b->f);
 
   /* --- Fix up the quotient too --- */
 
@@ -719,6 +840,100 @@ MPX_DOBIN(DO)
   return (ok);
 }
 
+static int tset(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  unsigned long n = *(unsigned long *)v[1].buf;
+  mp *r = *(mp **)v[2].buf;
+  mp *c;
+  int ok = 1;
+
+  c = mp_setbit2c(MP_NEW, a, n);
+  if (!MP_EQ(c, r)) {
+    ok = 0;
+    fprintf(stderr, "\n***setbit (set) failed");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 16);
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputs("\n*** c = ", stderr); mp_writefile(c, stderr, 16);
+    fputc('\n', stderr);
+  }
+  if (!mp_testbit2c(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n***setbit (test) failed");
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(r);
+  mp_drop(c);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);
+}
+
+static int tclr(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  unsigned long n = *(unsigned long *)v[1].buf;
+  mp *r = *(mp **)v[2].buf;
+  mp *c;
+  int ok = 1;
+
+  c = mp_clearbit2c(MP_NEW, a, n);
+  if (!MP_EQ(c, r)) {
+    ok = 0;
+    fprintf(stderr, "\n***clrbit (set) failed");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 16);
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputs("\n*** c = ", stderr); mp_writefile(c, stderr, 16);
+    fputc('\n', stderr);
+  }
+  if (mp_testbit2c(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n***clrbit (test) failed");
+    fprintf(stderr, "\n*** n  = %lu", n);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 16);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(c);
+  mp_drop(r);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);
+}
+
+static int tneg(dstr *v)
+{
+  mp *a = *(mp **)v[0].buf;
+  mp *r = *(mp **)v[1].buf;
+  int ok = 1;
+  mp *n = mp_neg(MP_NEW, a);
+  if (!MP_EQ(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n*** neg failed\n");
+    fputs("\n*** a  = ", stderr); mp_writefile(a, stderr, 10);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 10);
+    fputs("\n*** n  = ", stderr); mp_writefile(n, stderr, 10);
+    fputc('\n', stderr);
+  }
+  mp_drop(n);
+  n = mp_neg(a, a);
+  if (!MP_EQ(r, n)) {
+    ok = 0;
+    fprintf(stderr, "\n*** neg failed\n");
+    fputs("\n*** a* = ", stderr); mp_writefile(a, stderr, 10);
+    fputs("\n*** r  = ", stderr); mp_writefile(r, stderr, 10);
+    fputs("\n*** n  = ", stderr); mp_writefile(n, stderr, 10);
+    fputc('\n', stderr);
+  }
+  mp_drop(a);
+  mp_drop(r);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
+  return (ok);  
+}
+
 static int todd(dstr *v)
 {
   mp *a = *(mp **)v[0].buf;
@@ -741,6 +956,7 @@ static int todd(dstr *v)
   mp_drop(a);
   mp_drop(rt);
   mp_drop(t);
+  assert(mparena_count(MPARENA_GLOBAL) == 0);
   return (ok);
 }
 
@@ -749,12 +965,15 @@ static test_chunk tests[] = {
   { "lsr", tlsr, { &type_mp, &type_int, &type_mp, 0 } },
   { "lsl2c", tlsl2c, { &type_mp, &type_int, &type_mp, 0 } },
   { "lsr2c", tlsr2c, { &type_mp, &type_int, &type_mp, 0 } },
+  { "setbit", tset, { &type_mp, &type_ulong, &type_mp, 0 } },
+  { "clrbit", tclr, { &type_mp, &type_ulong, &type_mp, 0 } },
   { "add", tadd, { &type_mp, &type_mp, &type_mp, 0 } },
   { "sub", tsub, { &type_mp, &type_mp, &type_mp, 0 } },
   { "mul", tmul, { &type_mp, &type_mp, &type_mp, 0 } },
   { "div", tdiv, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
   { "bin2c", tbin, { &type_string, &type_mp, &type_mp, &type_mp, 0 } },
   { "odd", todd, { &type_mp, &type_uint32, &type_mp, 0 } },
+  { "neg", tneg, { &type_mp, &type_mp, 0 } },
   { 0, 0, { 0 } },
 };