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Diffstat (limited to 'libXfont/src/Type1/arith.c')
-rw-r--r-- | libXfont/src/Type1/arith.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/libXfont/src/Type1/arith.c b/libXfont/src/Type1/arith.c new file mode 100644 index 000000000..92a372a17 --- /dev/null +++ b/libXfont/src/Type1/arith.c @@ -0,0 +1,212 @@ +/* $Xorg: arith.c,v 1.3 2000/08/17 19:46:29 cpqbld Exp $ */ +/* Copyright International Business Machines, Corp. 1991 + * All Rights Reserved + * Copyright Lexmark International, Inc. 1991 + * All Rights Reserved + * + * License to use, copy, modify, and distribute this software and its + * documentation for any purpose and without fee is hereby granted, + * provided that the above copyright notice appear in all copies and that + * both that copyright notice and this permission notice appear in + * supporting documentation, and that the name of IBM or Lexmark not be + * used in advertising or publicity pertaining to distribution of the + * software without specific, written prior permission. + * + * IBM AND LEXMARK PROVIDE THIS SOFTWARE "AS IS", WITHOUT ANY WARRANTIES OF + * ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO ANY + * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, + * AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. THE ENTIRE RISK AS TO THE + * QUALITY AND PERFORMANCE OF THE SOFTWARE, INCLUDING ANY DUTY TO SUPPORT + * OR MAINTAIN, BELONGS TO THE LICENSEE. SHOULD ANY PORTION OF THE + * SOFTWARE PROVE DEFECTIVE, THE LICENSEE (NOT IBM OR LEXMARK) ASSUMES THE + * ENTIRE COST OF ALL SERVICING, REPAIR AND CORRECTION. IN NO EVENT SHALL + * IBM OR LEXMARK BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL + * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR + * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS + * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF + * THIS SOFTWARE. + */ +/* $XFree86: xc/lib/font/Type1/arith.c,v 1.6tsi Exp $ */ + + /* ARITH CWEB V0006 ******** */ +/* +:h1.ARITH Module - Portable Module for Multiple Precision Fixed Point Arithmetic + +This module provides division and multiplication of 64-bit fixed point +numbers. (To be more precise, the module works on numbers that take +two 'longs' to store. That is almost always equivalent to saying 64-bit +numbers.) + +Note: it is frequently easy and desirable to recode these functions in +assembly language for the particular processor being used, because +assembly language, unlike C, will have 64-bit multiply products and +64-bit dividends. This module is offered as a portable version. + +&author. Jeffrey B. Lotspiech (lotspiech@almaden.ibm.com) and Sten F. Andler + + +:h3.Include Files + +The included files are: +*/ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif +#ifdef FONTMODULE +# include "os.h" +#endif +#include "objects.h" +#include "spaces.h" +#include "arith.h" + + +/* +:h3. +*/ +/*SHARED LINE(S) ORIGINATED HERE*/ +/* +Reference for all algorithms: Donald E. Knuth, "The Art of Computer +Programming, Volume 2, Semi-Numerical Algorithms," Addison-Wesley Co., +Massachusetts, 1969, pp. 229-279. + +Knuth talks about a 'digit' being an arbitrary sized unit and a number +being a sequence of digits. We'll take a digit to be a 'short'. +The following assumption must be valid for these algorithms to work: +:ol. +:li.A 'long' is two 'short's. +:eol. +The following code is INDEPENDENT of: +:ol. +:li.The actual size of a short. +:li.Whether shorts and longs are stored most significant byte +first or least significant byte first. +:eol. + +SHORTSIZE is the number of bits in a short; LONGSIZE is the number of +bits in a long; MAXSHORT is the maximum unsigned short: +*/ +/*SHARED LINE(S) ORIGINATED HERE*/ +/* +ASSEMBLE concatenates two shorts to form a long: +*/ +#define ASSEMBLE(hi,lo) ((((unsigned long)hi)<<SHORTSIZE)+(lo)) +/* +HIGHDIGIT extracts the most significant short from a long; LOWDIGIT +extracts the least significant short from a long: +*/ +#define HIGHDIGIT(u) ((u)>>SHORTSIZE) +#define LOWDIGIT(u) ((u)&MAXSHORT) + +/* +SIGNBITON tests the high order bit of a long 'w': +*/ +#define SIGNBITON(w) (((long)w)<0) + +/*SHARED LINE(S) ORIGINATED HERE*/ + +/* +:h2.Double Long Arithmetic + +:h3.DLmult() - Multiply Two Longs to Yield a Double Long + +The two multiplicands must be positive. +*/ + +static void +DLmult(doublelong *product, unsigned long u, unsigned long v) +{ +#ifdef LONG64 +/* printf("DLmult(? ?, %lx, %lx)\n", u, v); */ + *product = u*v; +/* printf("DLmult returns %lx\n", *product); */ +#else + register unsigned long u1, u2; /* the digits of u */ + register unsigned long v1, v2; /* the digits of v */ + register unsigned int w1, w2, w3, w4; /* the digits of w */ + register unsigned long t; /* temporary variable */ +/* printf("DLmult(? ?, %x, %x)\n", u, v); */ + u1 = HIGHDIGIT(u); + u2 = LOWDIGIT(u); + v1 = HIGHDIGIT(v); + v2 = LOWDIGIT(v); + + if (v2 == 0) w4 = w3 = w2 = 0; + else + { + t = u2 * v2; + w4 = LOWDIGIT(t); + t = u1 * v2 + HIGHDIGIT(t); + w3 = LOWDIGIT(t); + w2 = HIGHDIGIT(t); + } + + if (v1 == 0) w1 = 0; + else + { + t = u2 * v1 + w3; + w3 = LOWDIGIT(t); + t = u1 * v1 + w2 + HIGHDIGIT(t); + w2 = LOWDIGIT(t); + w1 = HIGHDIGIT(t); + } + + product->high = ASSEMBLE(w1, w2); + product->low = ASSEMBLE(w3, w4); +#endif /* LONG64 else */ +} + +/* +:h3.DLrightshift() - Macro to Shift Double Long Right by N +*/ + +/*SHARED LINE(S) ORIGINATED HERE*/ + +/* +:h2.Fractional Pel Arithmetic +*/ +/* +:h3.FPmult() - Multiply Two Fractional Pel Values + +This funtion first calculates w = u * v to "doublelong" precision. +It then shifts w right by FRACTBITS bits, and checks that no +overflow will occur when the resulting value is passed back as +a fractpel. +*/ + +fractpel +FPmult(fractpel u, fractpel v) +{ + doublelong w; + register int negative = FALSE; /* sign flag */ +#ifdef LONG64 + register fractpel ret; +#endif + + if ((u == 0) || (v == 0)) return (0); + + + if (u < 0) {u = -u; negative = TRUE;} + if (v < 0) {v = -v; negative = !negative;} + + if (u == TOFRACTPEL(1)) return ((negative) ? -v : v); + if (v == TOFRACTPEL(1)) return ((negative) ? -u : u); + + DLmult(&w, u, v); + DLrightshift(w, FRACTBITS); +#ifndef LONG64 + if (w.high != 0 || SIGNBITON(w.low)) { + w.low = TOFRACTPEL(MAXSHORT); + } + + return ((negative) ? -w.low : w.low); +#else + if (w & 0xffffffff80000000L ) { + ret = TOFRACTPEL(MAXSHORT); + } + else + ret = (fractpel)w; + + return ((negative) ? -ret : ret); +#endif +} |