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Diffstat (limited to 'arch/parisc/math-emu/dfdiv.c')
| -rw-r--r-- | arch/parisc/math-emu/dfdiv.c | 387 |
1 files changed, 387 insertions, 0 deletions
diff --git a/arch/parisc/math-emu/dfdiv.c b/arch/parisc/math-emu/dfdiv.c new file mode 100644 index 000000000..239150dbe --- /dev/null +++ b/arch/parisc/math-emu/dfdiv.c @@ -0,0 +1,387 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Linux/PA-RISC Project (http://www.parisc-linux.org/) + * + * Floating-point emulation code + * Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org> + */ +/* + * BEGIN_DESC + * + * File: + * @(#) pa/spmath/dfdiv.c $Revision: 1.1 $ + * + * Purpose: + * Double Precision Floating-point Divide + * + * External Interfaces: + * dbl_fdiv(srcptr1,srcptr2,dstptr,status) + * + * Internal Interfaces: + * + * Theory: + * <<please update with a overview of the operation of this file>> + * + * END_DESC +*/ + + +#include "float.h" +#include "dbl_float.h" + +/* + * Double Precision Floating-point Divide + */ + +int +dbl_fdiv (dbl_floating_point * srcptr1, dbl_floating_point * srcptr2, + dbl_floating_point * dstptr, unsigned int *status) +{ + register unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2; + register unsigned int opnd3p1, opnd3p2, resultp1, resultp2; + register int dest_exponent, count; + register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; + boolean is_tiny; + + Dbl_copyfromptr(srcptr1,opnd1p1,opnd1p2); + Dbl_copyfromptr(srcptr2,opnd2p1,opnd2p2); + /* + * set sign bit of result + */ + if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1)) + Dbl_setnegativezerop1(resultp1); + else Dbl_setzerop1(resultp1); + /* + * check first operand for NaN's or infinity + */ + if (Dbl_isinfinity_exponent(opnd1p1)) { + if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { + if (Dbl_isnotnan(opnd2p1,opnd2p2)) { + if (Dbl_isinfinity(opnd2p1,opnd2p2)) { + /* + * invalid since both operands + * are infinity + */ + if (Is_invalidtrap_enabled()) + return(INVALIDEXCEPTION); + Set_invalidflag(); + Dbl_makequietnan(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + /* + * return infinity + */ + Dbl_setinfinity_exponentmantissa(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + } + else { + /* + * is NaN; signaling or quiet? + */ + if (Dbl_isone_signaling(opnd1p1)) { + /* trap if INVALIDTRAP enabled */ + if (Is_invalidtrap_enabled()) + return(INVALIDEXCEPTION); + /* make NaN quiet */ + Set_invalidflag(); + Dbl_set_quiet(opnd1p1); + } + /* + * is second operand a signaling NaN? + */ + else if (Dbl_is_signalingnan(opnd2p1)) { + /* trap if INVALIDTRAP enabled */ + if (Is_invalidtrap_enabled()) + return(INVALIDEXCEPTION); + /* make NaN quiet */ + Set_invalidflag(); + Dbl_set_quiet(opnd2p1); + Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); + return(NOEXCEPTION); + } + /* + * return quiet NaN + */ + Dbl_copytoptr(opnd1p1,opnd1p2,dstptr); + return(NOEXCEPTION); + } + } + /* + * check second operand for NaN's or infinity + */ + if (Dbl_isinfinity_exponent(opnd2p1)) { + if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) { + /* + * return zero + */ + Dbl_setzero_exponentmantissa(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + /* + * is NaN; signaling or quiet? + */ + if (Dbl_isone_signaling(opnd2p1)) { + /* trap if INVALIDTRAP enabled */ + if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); + /* make NaN quiet */ + Set_invalidflag(); + Dbl_set_quiet(opnd2p1); + } + /* + * return quiet NaN + */ + Dbl_copytoptr(opnd2p1,opnd2p2,dstptr); + return(NOEXCEPTION); + } + /* + * check for division by zero + */ + if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) { + if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) { + /* invalid since both operands are zero */ + if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); + Set_invalidflag(); + Dbl_makequietnan(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + if (Is_divisionbyzerotrap_enabled()) + return(DIVISIONBYZEROEXCEPTION); + Set_divisionbyzeroflag(); + Dbl_setinfinity_exponentmantissa(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + /* + * Generate exponent + */ + dest_exponent = Dbl_exponent(opnd1p1) - Dbl_exponent(opnd2p1) + DBL_BIAS; + + /* + * Generate mantissa + */ + if (Dbl_isnotzero_exponent(opnd1p1)) { + /* set hidden bit */ + Dbl_clear_signexponent_set_hidden(opnd1p1); + } + else { + /* check for zero */ + if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) { + Dbl_setzero_exponentmantissa(resultp1,resultp2); + Dbl_copytoptr(resultp1,resultp2,dstptr); + return(NOEXCEPTION); + } + /* is denormalized, want to normalize */ + Dbl_clear_signexponent(opnd1p1); + Dbl_leftshiftby1(opnd1p1,opnd1p2); + Dbl_normalize(opnd1p1,opnd1p2,dest_exponent); + } + /* opnd2 needs to have hidden bit set with msb in hidden bit */ + if (Dbl_isnotzero_exponent(opnd2p1)) { + Dbl_clear_signexponent_set_hidden(opnd2p1); + } + else { + /* is denormalized; want to normalize */ + Dbl_clear_signexponent(opnd2p1); + Dbl_leftshiftby1(opnd2p1,opnd2p2); + while (Dbl_iszero_hiddenhigh7mantissa(opnd2p1)) { + dest_exponent+=8; + Dbl_leftshiftby8(opnd2p1,opnd2p2); + } + if (Dbl_iszero_hiddenhigh3mantissa(opnd2p1)) { + dest_exponent+=4; + Dbl_leftshiftby4(opnd2p1,opnd2p2); + } + while (Dbl_iszero_hidden(opnd2p1)) { + dest_exponent++; + Dbl_leftshiftby1(opnd2p1,opnd2p2); + } + } + + /* Divide the source mantissas */ + + /* + * A non-restoring divide algorithm is used. + */ + Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); + Dbl_setzero(opnd3p1,opnd3p2); + for (count=1; count <= DBL_P && (opnd1p1 || opnd1p2); count++) { + Dbl_leftshiftby1(opnd1p1,opnd1p2); + Dbl_leftshiftby1(opnd3p1,opnd3p2); + if (Dbl_iszero_sign(opnd1p1)) { + Dbl_setone_lowmantissap2(opnd3p2); + Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); + } + else { + Twoword_add(opnd1p1, opnd1p2, opnd2p1, opnd2p2); + } + } + if (count <= DBL_P) { + Dbl_leftshiftby1(opnd3p1,opnd3p2); + Dbl_setone_lowmantissap2(opnd3p2); + Dbl_leftshift(opnd3p1,opnd3p2,(DBL_P-count)); + if (Dbl_iszero_hidden(opnd3p1)) { + Dbl_leftshiftby1(opnd3p1,opnd3p2); + dest_exponent--; + } + } + else { + if (Dbl_iszero_hidden(opnd3p1)) { + /* need to get one more bit of result */ + Dbl_leftshiftby1(opnd1p1,opnd1p2); + Dbl_leftshiftby1(opnd3p1,opnd3p2); + if (Dbl_iszero_sign(opnd1p1)) { + Dbl_setone_lowmantissap2(opnd3p2); + Twoword_subtract(opnd1p1,opnd1p2,opnd2p1,opnd2p2); + } + else { + Twoword_add(opnd1p1,opnd1p2,opnd2p1,opnd2p2); + } + dest_exponent--; + } + if (Dbl_iszero_sign(opnd1p1)) guardbit = TRUE; + stickybit = Dbl_allp1(opnd1p1) || Dbl_allp2(opnd1p2); + } + inexact = guardbit | stickybit; + + /* + * round result + */ + if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { + Dbl_clear_signexponent(opnd3p1); + switch (Rounding_mode()) { + case ROUNDPLUS: + if (Dbl_iszero_sign(resultp1)) + Dbl_increment(opnd3p1,opnd3p2); + break; + case ROUNDMINUS: + if (Dbl_isone_sign(resultp1)) + Dbl_increment(opnd3p1,opnd3p2); + break; + case ROUNDNEAREST: + if (guardbit && (stickybit || + Dbl_isone_lowmantissap2(opnd3p2))) { + Dbl_increment(opnd3p1,opnd3p2); + } + } + if (Dbl_isone_hidden(opnd3p1)) dest_exponent++; + } + Dbl_set_mantissa(resultp1,resultp2,opnd3p1,opnd3p2); + + /* + * Test for overflow + */ + if (dest_exponent >= DBL_INFINITY_EXPONENT) { + /* trap if OVERFLOWTRAP enabled */ + if (Is_overflowtrap_enabled()) { + /* + * Adjust bias of result + */ + Dbl_setwrapped_exponent(resultp1,dest_exponent,ovfl); + Dbl_copytoptr(resultp1,resultp2,dstptr); + if (inexact) + if (Is_inexacttrap_enabled()) + return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); + else Set_inexactflag(); + return(OVERFLOWEXCEPTION); + } + Set_overflowflag(); + /* set result to infinity or largest number */ + Dbl_setoverflow(resultp1,resultp2); + inexact = TRUE; + } + /* + * Test for underflow + */ + else if (dest_exponent <= 0) { + /* trap if UNDERFLOWTRAP enabled */ + if (Is_underflowtrap_enabled()) { + /* + * Adjust bias of result + */ + Dbl_setwrapped_exponent(resultp1,dest_exponent,unfl); + Dbl_copytoptr(resultp1,resultp2,dstptr); + if (inexact) + if (Is_inexacttrap_enabled()) + return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION); + else Set_inexactflag(); + return(UNDERFLOWEXCEPTION); + } + + /* Determine if should set underflow flag */ + is_tiny = TRUE; + if (dest_exponent == 0 && inexact) { + switch (Rounding_mode()) { + case ROUNDPLUS: + if (Dbl_iszero_sign(resultp1)) { + Dbl_increment(opnd3p1,opnd3p2); + if (Dbl_isone_hiddenoverflow(opnd3p1)) + is_tiny = FALSE; + Dbl_decrement(opnd3p1,opnd3p2); + } + break; + case ROUNDMINUS: + if (Dbl_isone_sign(resultp1)) { + Dbl_increment(opnd3p1,opnd3p2); + if (Dbl_isone_hiddenoverflow(opnd3p1)) + is_tiny = FALSE; + Dbl_decrement(opnd3p1,opnd3p2); + } + break; + case ROUNDNEAREST: + if (guardbit && (stickybit || + Dbl_isone_lowmantissap2(opnd3p2))) { + Dbl_increment(opnd3p1,opnd3p2); + if (Dbl_isone_hiddenoverflow(opnd3p1)) + is_tiny = FALSE; + Dbl_decrement(opnd3p1,opnd3p2); + } + break; + } + } + + /* + * denormalize result or set to signed zero + */ + stickybit = inexact; + Dbl_denormalize(opnd3p1,opnd3p2,dest_exponent,guardbit, + stickybit,inexact); + + /* return rounded number */ + if (inexact) { + switch (Rounding_mode()) { + case ROUNDPLUS: + if (Dbl_iszero_sign(resultp1)) { + Dbl_increment(opnd3p1,opnd3p2); + } + break; + case ROUNDMINUS: + if (Dbl_isone_sign(resultp1)) { + Dbl_increment(opnd3p1,opnd3p2); + } + break; + case ROUNDNEAREST: + if (guardbit && (stickybit || + Dbl_isone_lowmantissap2(opnd3p2))) { + Dbl_increment(opnd3p1,opnd3p2); + } + break; + } + if (is_tiny) Set_underflowflag(); + } + Dbl_set_exponentmantissa(resultp1,resultp2,opnd3p1,opnd3p2); + } + else Dbl_set_exponent(resultp1,dest_exponent); + Dbl_copytoptr(resultp1,resultp2,dstptr); + + /* check for inexact */ + if (inexact) { + if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); + else Set_inexactflag(); + } + return(NOEXCEPTION); +} |