| // 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/sfdiv.c $Revision: 1.1 $ |
| * |
| * Purpose: |
| * Single Precision Floating-point Divide |
| * |
| * External Interfaces: |
| * sgl_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 "sgl_float.h" |
| |
| /* |
| * Single Precision Floating-point Divide |
| */ |
| |
| int |
| sgl_fdiv (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2, |
| sgl_floating_point * dstptr, unsigned int *status) |
| { |
| register unsigned int opnd1, opnd2, opnd3, result; |
| register int dest_exponent, count; |
| register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; |
| boolean is_tiny; |
| |
| opnd1 = *srcptr1; |
| opnd2 = *srcptr2; |
| /* |
| * set sign bit of result |
| */ |
| if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result); |
| else Sgl_setzero(result); |
| /* |
| * check first operand for NaN's or infinity |
| */ |
| if (Sgl_isinfinity_exponent(opnd1)) { |
| if (Sgl_iszero_mantissa(opnd1)) { |
| if (Sgl_isnotnan(opnd2)) { |
| if (Sgl_isinfinity(opnd2)) { |
| /* |
| * invalid since both operands |
| * are infinity |
| */ |
| if (Is_invalidtrap_enabled()) |
| return(INVALIDEXCEPTION); |
| Set_invalidflag(); |
| Sgl_makequietnan(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| /* |
| * return infinity |
| */ |
| Sgl_setinfinity_exponentmantissa(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| } |
| else { |
| /* |
| * is NaN; signaling or quiet? |
| */ |
| if (Sgl_isone_signaling(opnd1)) { |
| /* trap if INVALIDTRAP enabled */ |
| if (Is_invalidtrap_enabled()) |
| return(INVALIDEXCEPTION); |
| /* make NaN quiet */ |
| Set_invalidflag(); |
| Sgl_set_quiet(opnd1); |
| } |
| /* |
| * is second operand a signaling NaN? |
| */ |
| else if (Sgl_is_signalingnan(opnd2)) { |
| /* trap if INVALIDTRAP enabled */ |
| if (Is_invalidtrap_enabled()) |
| return(INVALIDEXCEPTION); |
| /* make NaN quiet */ |
| Set_invalidflag(); |
| Sgl_set_quiet(opnd2); |
| *dstptr = opnd2; |
| return(NOEXCEPTION); |
| } |
| /* |
| * return quiet NaN |
| */ |
| *dstptr = opnd1; |
| return(NOEXCEPTION); |
| } |
| } |
| /* |
| * check second operand for NaN's or infinity |
| */ |
| if (Sgl_isinfinity_exponent(opnd2)) { |
| if (Sgl_iszero_mantissa(opnd2)) { |
| /* |
| * return zero |
| */ |
| Sgl_setzero_exponentmantissa(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| /* |
| * is NaN; signaling or quiet? |
| */ |
| if (Sgl_isone_signaling(opnd2)) { |
| /* trap if INVALIDTRAP enabled */ |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| /* make NaN quiet */ |
| Set_invalidflag(); |
| Sgl_set_quiet(opnd2); |
| } |
| /* |
| * return quiet NaN |
| */ |
| *dstptr = opnd2; |
| return(NOEXCEPTION); |
| } |
| /* |
| * check for division by zero |
| */ |
| if (Sgl_iszero_exponentmantissa(opnd2)) { |
| if (Sgl_iszero_exponentmantissa(opnd1)) { |
| /* invalid since both operands are zero */ |
| if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
| Set_invalidflag(); |
| Sgl_makequietnan(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| if (Is_divisionbyzerotrap_enabled()) |
| return(DIVISIONBYZEROEXCEPTION); |
| Set_divisionbyzeroflag(); |
| Sgl_setinfinity_exponentmantissa(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| /* |
| * Generate exponent |
| */ |
| dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS; |
| |
| /* |
| * Generate mantissa |
| */ |
| if (Sgl_isnotzero_exponent(opnd1)) { |
| /* set hidden bit */ |
| Sgl_clear_signexponent_set_hidden(opnd1); |
| } |
| else { |
| /* check for zero */ |
| if (Sgl_iszero_mantissa(opnd1)) { |
| Sgl_setzero_exponentmantissa(result); |
| *dstptr = result; |
| return(NOEXCEPTION); |
| } |
| /* is denormalized; want to normalize */ |
| Sgl_clear_signexponent(opnd1); |
| Sgl_leftshiftby1(opnd1); |
| Sgl_normalize(opnd1,dest_exponent); |
| } |
| /* opnd2 needs to have hidden bit set with msb in hidden bit */ |
| if (Sgl_isnotzero_exponent(opnd2)) { |
| Sgl_clear_signexponent_set_hidden(opnd2); |
| } |
| else { |
| /* is denormalized; want to normalize */ |
| Sgl_clear_signexponent(opnd2); |
| Sgl_leftshiftby1(opnd2); |
| while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) { |
| Sgl_leftshiftby8(opnd2); |
| dest_exponent += 8; |
| } |
| if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) { |
| Sgl_leftshiftby4(opnd2); |
| dest_exponent += 4; |
| } |
| while(Sgl_iszero_hidden(opnd2)) { |
| Sgl_leftshiftby1(opnd2); |
| dest_exponent += 1; |
| } |
| } |
| |
| /* Divide the source mantissas */ |
| |
| /* |
| * A non_restoring divide algorithm is used. |
| */ |
| Sgl_subtract(opnd1,opnd2,opnd1); |
| Sgl_setzero(opnd3); |
| for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) { |
| Sgl_leftshiftby1(opnd1); |
| Sgl_leftshiftby1(opnd3); |
| if (Sgl_iszero_sign(opnd1)) { |
| Sgl_setone_lowmantissa(opnd3); |
| Sgl_subtract(opnd1,opnd2,opnd1); |
| } |
| else Sgl_addition(opnd1,opnd2,opnd1); |
| } |
| if (count <= SGL_P) { |
| Sgl_leftshiftby1(opnd3); |
| Sgl_setone_lowmantissa(opnd3); |
| Sgl_leftshift(opnd3,SGL_P-count); |
| if (Sgl_iszero_hidden(opnd3)) { |
| Sgl_leftshiftby1(opnd3); |
| dest_exponent--; |
| } |
| } |
| else { |
| if (Sgl_iszero_hidden(opnd3)) { |
| /* need to get one more bit of result */ |
| Sgl_leftshiftby1(opnd1); |
| Sgl_leftshiftby1(opnd3); |
| if (Sgl_iszero_sign(opnd1)) { |
| Sgl_setone_lowmantissa(opnd3); |
| Sgl_subtract(opnd1,opnd2,opnd1); |
| } |
| else Sgl_addition(opnd1,opnd2,opnd1); |
| dest_exponent--; |
| } |
| if (Sgl_iszero_sign(opnd1)) guardbit = TRUE; |
| stickybit = Sgl_all(opnd1); |
| } |
| inexact = guardbit | stickybit; |
| |
| /* |
| * round result |
| */ |
| if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { |
| Sgl_clear_signexponent(opnd3); |
| switch (Rounding_mode()) { |
| case ROUNDPLUS: |
| if (Sgl_iszero_sign(result)) |
| Sgl_increment_mantissa(opnd3); |
| break; |
| case ROUNDMINUS: |
| if (Sgl_isone_sign(result)) |
| Sgl_increment_mantissa(opnd3); |
| break; |
| case ROUNDNEAREST: |
| if (guardbit) { |
| if (stickybit || Sgl_isone_lowmantissa(opnd3)) |
| Sgl_increment_mantissa(opnd3); |
| } |
| } |
| if (Sgl_isone_hidden(opnd3)) dest_exponent++; |
| } |
| Sgl_set_mantissa(result,opnd3); |
| |
| /* |
| * Test for overflow |
| */ |
| if (dest_exponent >= SGL_INFINITY_EXPONENT) { |
| /* trap if OVERFLOWTRAP enabled */ |
| if (Is_overflowtrap_enabled()) { |
| /* |
| * Adjust bias of result |
| */ |
| Sgl_setwrapped_exponent(result,dest_exponent,ovfl); |
| *dstptr = result; |
| if (inexact) |
| if (Is_inexacttrap_enabled()) |
| return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); |
| else Set_inexactflag(); |
| return(OVERFLOWEXCEPTION); |
| } |
| Set_overflowflag(); |
| /* set result to infinity or largest number */ |
| Sgl_setoverflow(result); |
| inexact = TRUE; |
| } |
| /* |
| * Test for underflow |
| */ |
| else if (dest_exponent <= 0) { |
| /* trap if UNDERFLOWTRAP enabled */ |
| if (Is_underflowtrap_enabled()) { |
| /* |
| * Adjust bias of result |
| */ |
| Sgl_setwrapped_exponent(result,dest_exponent,unfl); |
| *dstptr = result; |
| 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 (Sgl_iszero_sign(result)) { |
| Sgl_increment(opnd3); |
| if (Sgl_isone_hiddenoverflow(opnd3)) |
| is_tiny = FALSE; |
| Sgl_decrement(opnd3); |
| } |
| break; |
| case ROUNDMINUS: |
| if (Sgl_isone_sign(result)) { |
| Sgl_increment(opnd3); |
| if (Sgl_isone_hiddenoverflow(opnd3)) |
| is_tiny = FALSE; |
| Sgl_decrement(opnd3); |
| } |
| break; |
| case ROUNDNEAREST: |
| if (guardbit && (stickybit || |
| Sgl_isone_lowmantissa(opnd3))) { |
| Sgl_increment(opnd3); |
| if (Sgl_isone_hiddenoverflow(opnd3)) |
| is_tiny = FALSE; |
| Sgl_decrement(opnd3); |
| } |
| break; |
| } |
| } |
| |
| /* |
| * denormalize result or set to signed zero |
| */ |
| stickybit = inexact; |
| Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact); |
| |
| /* return rounded number */ |
| if (inexact) { |
| switch (Rounding_mode()) { |
| case ROUNDPLUS: |
| if (Sgl_iszero_sign(result)) { |
| Sgl_increment(opnd3); |
| } |
| break; |
| case ROUNDMINUS: |
| if (Sgl_isone_sign(result)) { |
| Sgl_increment(opnd3); |
| } |
| break; |
| case ROUNDNEAREST: |
| if (guardbit && (stickybit || |
| Sgl_isone_lowmantissa(opnd3))) { |
| Sgl_increment(opnd3); |
| } |
| break; |
| } |
| if (is_tiny) Set_underflowflag(); |
| } |
| Sgl_set_exponentmantissa(result,opnd3); |
| } |
| else Sgl_set_exponent(result,dest_exponent); |
| *dstptr = result; |
| /* check for inexact */ |
| if (inexact) { |
| if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); |
| else Set_inexactflag(); |
| } |
| return(NOEXCEPTION); |
| } |
