Initial commit.

1 files changed, 244 insertions, 0 deletions

diff --git a/arith.c b/arith.c
new file mode 100644
index 0000000..784946f
--- /dev/null
+++ b/arith.c
@@ -0,0 +1,244 @@
+/*
+ *  Compface - 48x48x1 image compression and decompression
+ *
+ *  Copyright (c) James Ashton - Sydney University - June 1990.
+ *
+ *  Written 11th November 1989.
+ *
+ *  Permission is given to distribute these sources, as long as the
+ *  copyright messages are not removed, and no monies are exchanged. 
+ *
+ *  No responsibility is taken for any errors on inaccuracies inherent
+ *  either to the comments or the code of this program, but if reported
+ *  to me, then an attempt will be made to fix them.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "compface.h"
+
+void
+RevPush(p)
+Prob *p;
+{
+	if (NumProbs >= PIXELS * 2 - 1)
+		longjmp(comp_env, ERR_INTERNAL);
+	ProbBuf[NumProbs++] = p;
+}
+ 
+void
+BigPush(p)
+Prob *p;
+{
+	static WORD tmp;
+
+	BigDiv(p->p_range, &tmp);
+	BigMul(0);
+	BigAdd(tmp + p->p_offset);
+}
+
+int
+BigPop(p)
+register Prob *p; 
+{
+	static WORD tmp;
+	register int i;
+
+	BigDiv(0, &tmp);
+	i = 0;
+	while ((tmp < p->p_offset) || (tmp >= p->p_range + p->p_offset))
+	{
+		p++;
+		i++;
+	}
+	BigMul(p->p_range);
+	BigAdd(tmp - p->p_offset);
+	return i;
+}
+
+#ifdef DEBUG
+/* Print a BigInt in HexaDecimal
+ */
+void
+BigPrint()
+{
+	register int i, c, count;
+	register WORD *w;
+
+	count = 0;
+	w = B.b_word + (i = B.b_words);
+	while (i--)
+	{
+		w--;
+		c = *((*w >> 4) + HexDigits);
+		putc(c, stderr);
+		c = *((*w & 0xf) + HexDigits);
+		putc(c, stderr);
+		if (++count >= 36)
+		{
+			putc('\\', stderr);
+			putc('\n', stderr);
+			count = 0;
+		}
+	}
+	putc('\n', stderr);
+}
+#endif
+
+/* Divide B by a storing the result in B and the remainder in the word
+ * pointer to by r
+ */
+void
+BigDiv(a, r)
+register WORD a, *r;
+{
+	register int i;
+	register WORD *w;
+	register COMP c, d;
+
+	a &= WORDMASK;
+	if ((a == 1) || (B.b_words == 0))
+	{
+		*r = 0;
+		return;
+	}
+	if (a == 0)	/* treat this as a == WORDCARRY */
+	{			/* and just shift everything right a WORD */
+		i = --B.b_words;
+		w = B.b_word;
+		*r = *w;
+		while (i--)
+		{
+			*w = *(w + 1);
+			w++;
+		}
+		*w = 0;
+		return;
+	}
+	w = B.b_word + (i = B.b_words);
+	c = 0;
+	while (i--)
+	{
+		c <<= BITSPERWORD;
+		c += (COMP)*--w;
+		d = c / (COMP)a;
+		c = c % (COMP)a;
+		*w = (WORD)(d & WORDMASK);
+	}
+	*r = c;
+	if (B.b_word[B.b_words - 1] == 0)
+		B.b_words--;
+}
+
+/* Multiply a by B storing the result in B
+ */
+void
+BigMul(a)
+register WORD a;
+{
+	register int i;
+	register WORD *w;
+	register COMP c;
+
+	a &= WORDMASK;
+	if ((a == 1) || (B.b_words == 0))
+		return;
+	if (a == 0)	/* treat this as a == WORDCARRY */
+	{			/* and just shift everything left a WORD */
+		if ((i = B.b_words++) >= MAXWORDS - 1)
+			longjmp(comp_env, ERR_INTERNAL);
+		w = B.b_word + i;
+		while (i--)
+		{
+			*w = *(w - 1);
+			w--;
+		}
+		*w = 0;
+		return;
+	}
+	i = B.b_words;
+	w = B.b_word;
+	c = 0;
+	while (i--)
+	{
+		c += (COMP)*w * (COMP)a;
+		*(w++) = (WORD)(c & WORDMASK);
+		c >>= BITSPERWORD;
+	}
+	if (c)
+	{
+		if (B.b_words++ >= MAXWORDS)
+			longjmp(comp_env, ERR_INTERNAL);
+		*w = (COMP)(c & WORDMASK);
+	}
+}
+
+#if 0
+/* Subtract a from B storing the result in B
+ */
+void
+BigSub(a)
+WORD a;
+{
+	register int i;
+	register WORD *w;
+	register COMP c;
+
+	a &= WORDMASK;
+	if (a == 0)
+		return;
+	i = 1;
+	w = B.b_word;
+	c = (COMP)*w - (COMP)a;
+	*w = (WORD)(c & WORDMASK);
+	while (c & WORDCARRY)
+	{
+		if (i >= B.b_words)
+			longjmp(comp_env, ERR_INTERNAL);
+		c = (COMP)*++w - 1;
+		*w = (WORD)(c & WORDMASK);
+		i++;
+	}
+	if ((i == B.b_words) && (*w == 0) && (i > 0))
+		B.b_words--;
+}
+#endif
+
+/* Add to a to B storing the result in B
+ */
+void
+BigAdd(a)
+WORD a;
+{
+	register int i;
+	register WORD *w;
+	register COMP c;
+
+	a &= WORDMASK;
+	if (a == 0)
+		return;
+	i = 0;
+	w = B.b_word;
+	c = a;
+	while ((i < B.b_words) && c)
+	{
+		c += (COMP)*w;
+		*w++ = (WORD)(c & WORDMASK);
+		c >>= BITSPERWORD;
+		i++;
+	}
+	if ((i == B.b_words) && c)
+	{
+		if (B.b_words++ >= MAXWORDS)
+			longjmp(comp_env, ERR_INTERNAL);
+		*w = (COMP)(c & WORDMASK);
+	}
+}
+
+void
+BigClear()
+{
+	B.b_words = 0;
+}