1 files changed, 78 insertions, 0 deletions
diff --git a/ic-reals-6.3/base/digitHandling.c b/ic-reals-6.3/base/digitHandling.c
new file mode 100644
index 0000000..79e9dfb
--- /dev/null
+++ b/ic-reals-6.3/base/digitHandling.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2000, Imperial College
+ *
+ * This file is part of the Imperial College Exact Real Arithmetic Library.
+ * See the copyright notice included in the distribution for conditions
+ * of use.
+ */
+
+#include <stdio.h>
+#include "real.h"
+#include "real-impl.h"
+
+/*
+ * For a real that has been forced to a stream (by force_R_Digs)
+ * this function retrieves the sign and the most significant digit information.
+ */
+void
+retrieveInfo(Real x, Sign *sign, int *count, mpz_t digits)
+{
+	Real derefToStrm(Real);
+
+	x = derefToStrm(x);
+
+	if (x == NULL)
+		Error(FATAL, E_INT, "retrieveInfo", "argument not forced");
+
+	if (x->gen.tag.type == SIGNX) {
+		*sign = x->signX.tag.value;
+		x = x->signX.x;
+	}
+	else
+		*sign = SPOS;
+
+	if ((x->gen.tag.type = DIGSX)) {
+		*count = x->digsX.count;
+#ifdef PACK_DIGITS
+		if (*count <= DIGITS_PER_WORD)
+        	mpz_set_si(digits, x->digsX.word.small);
+    	else
+#endif
+        	mpz_set(digits, x->digsX.word.big);
+	}
+	else
+		Error(FATAL, E_INT, "retrieveInfo",
+				"no information has been forced from the argument");
+}
+
+/*
+ * Given a characteristic pair (c,n) where n is the number
+ * of digits recorded in c, this function returns the most significant
+ * digit yielding also (c', n-1)
+ */
+Digit
+takeDigit(int *count, mpz_t digits)
+{
+	Digit digit;
+
+	if (*count > 0)
+	  mpz_tdiv_q_2exp(tmpa_z, digits, *count - 1);
+	if (mpz_cmp_ui(tmpa_z, 0) == 0)
+	  digit = DZERO;
+	else
+	  if (mpz_cmp_ui(tmpa_z, 1) == 0)
+	    digit = DPOS;
+	  else
+	    if (mpz_cmp_si(tmpa_z, -1) == 0)
+	      digit = DNEG;
+	    else {
+	      Error(FATAL, E_INT, "takeDigit",
+		    "characteristic pair is not well formed");
+	      digit = DZERO;
+	    }
+
+	mpz_mul_2exp(tmpa_z, tmpa_z, *count - 1);
+	mpz_sub(digits, digits, tmpa_z);
+	*count = *count - 1;
+	return digit;
+}