Subversion Repositories or1k

/*
 * Copyright (C) 2000 Hewlett-Packard Co
 * Copyright (C) 2000 David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 32-bit integer division.
 *
 * This code is based on the application note entitled "Divide, Square Root
 * and Remainder Algorithms for the IA-64 Architecture".  This document
 * is available as Intel document number 248725-002 or via the web at
 * http://developer.intel.com/software/opensource/numerics/
 *
 * For more details on the theory behind these algorithms, see "IA-64
 * and Elementary Functions" by Peter Markstein; HP Professional Books
 * (http://www.hp.com/go/retailbooks/)
 */

#include <asm/asmmacro.h>

#ifdef MODULO
# define OP     mod
#else
# define OP     div
#endif

#ifdef UNSIGNED
# define SGN    u
# define EXTEND zxt4
# define INT_TO_FP(a,b) fcvt.xuf.s1 a=b
# define FP_TO_INT(a,b) fcvt.fxu.trunc.s1 a=b
#else
# define SGN
# define EXTEND sxt4
# define INT_TO_FP(a,b) fcvt.xf a=b
# define FP_TO_INT(a,b) fcvt.fx.trunc.s1 a=b
#endif

#define PASTE1(a,b)     a##b
#define PASTE(a,b)      PASTE1(a,b)
#define NAME            PASTE(PASTE(__,SGN),PASTE(OP,si3))

GLOBAL_ENTRY(NAME)
        .regstk 2,0,0,0
        // Transfer inputs to FP registers.
        mov r2 = 0xffdd                 // r2 = -34 + 65535 (fp reg format bias)
        EXTEND in0 = in0                // in0 = a
        EXTEND in1 = in1                // in1 = b
        ;;
        setf.sig f8 = in0
        setf.sig f9 = in1
#ifdef MODULO
        sub in1 = r0, in1               // in1 = -b
#endif
        ;;
        // Convert the inputs to FP, to avoid FP software-assist faults.
        INT_TO_FP(f8, f8)
        INT_TO_FP(f9, f9)
        ;;
        setf.exp f7 = r2                // f7 = 2^-34
        frcpa.s1 f6, p6 = f8, f9        // y0 = frcpa(b)
        ;;
(p6)    fmpy.s1 f8 = f8, f6             // q0 = a*y0
(p6)    fnma.s1 f6 = f9, f6, f1         // e0 = -b*y0 + 1 
        ;;
#ifdef MODULO
        setf.sig f9 = in1               // f9 = -b
#endif
(p6)    fma.s1 f8 = f6, f8, f8          // q1 = e0*q0 + q0
(p6)    fma.s1 f6 = f6, f6, f7          // e1 = e0*e0 + 2^-34
        ;;
#ifdef MODULO
        setf.sig f7 = in0
#endif
(p6)    fma.s1 f6 = f6, f8, f8          // q2 = e1*q1 + q1
        ;;
        FP_TO_INT(f6, f6)               // q = trunc(q2)
        ;;
#ifdef MODULO
        xma.l f6 = f6, f9, f7           // r = q*(-b) + a
        ;;
#endif
        getf.sig r8 = f6                // transfer result to result register
        br.ret.sptk.many rp
END(NAME)