diff options
Diffstat (limited to 'arch/x86/math-emu/reg_divide.c')
| -rw-r--r-- | arch/x86/math-emu/reg_divide.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/arch/x86/math-emu/reg_divide.c b/arch/x86/math-emu/reg_divide.c new file mode 100644 index 000000000..08c2f6de0 --- /dev/null +++ b/arch/x86/math-emu/reg_divide.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0 +/*---------------------------------------------------------------------------+ + | reg_divide.c | + | | + | Divide one FPU_REG by another and put the result in a destination FPU_REG.| + | | + | Copyright (C) 1996 | + | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | + | E-mail billm@jacobi.maths.monash.edu.au | + | | + | Return value is the tag of the answer, or-ed with FPU_Exception if | + | one was raised, or -1 on internal error. | + | | + +---------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------+ + | The destination may be any FPU_REG, including one of the source FPU_REGs. | + +---------------------------------------------------------------------------*/ + +#include "exception.h" +#include "reg_constant.h" +#include "fpu_emu.h" +#include "fpu_system.h" + +/* + Divide one register by another and put the result into a third register. + */ +int FPU_div(int flags, int rm, int control_w) +{ + FPU_REG x, y; + FPU_REG const *a, *b, *st0_ptr, *st_ptr; + FPU_REG *dest; + u_char taga, tagb, signa, signb, sign, saved_sign; + int tag, deststnr; + + if (flags & DEST_RM) + deststnr = rm; + else + deststnr = 0; + + if (flags & REV) { + b = &st(0); + st0_ptr = b; + tagb = FPU_gettag0(); + if (flags & LOADED) { + a = (FPU_REG *) rm; + taga = flags & 0x0f; + } else { + a = &st(rm); + st_ptr = a; + taga = FPU_gettagi(rm); + } + } else { + a = &st(0); + st0_ptr = a; + taga = FPU_gettag0(); + if (flags & LOADED) { + b = (FPU_REG *) rm; + tagb = flags & 0x0f; + } else { + b = &st(rm); + st_ptr = b; + tagb = FPU_gettagi(rm); + } + } + + signa = getsign(a); + signb = getsign(b); + + sign = signa ^ signb; + + dest = &st(deststnr); + saved_sign = getsign(dest); + + if (!(taga | tagb)) { + /* Both regs Valid, this should be the most common case. */ + reg_copy(a, &x); + reg_copy(b, &y); + setpositive(&x); + setpositive(&y); + tag = FPU_u_div(&x, &y, dest, control_w, sign); + + if (tag < 0) + return tag; + + FPU_settagi(deststnr, tag); + return tag; + } + + if (taga == TAG_Special) + taga = FPU_Special(a); + if (tagb == TAG_Special) + tagb = FPU_Special(b); + + if (((taga == TAG_Valid) && (tagb == TW_Denormal)) + || ((taga == TW_Denormal) && (tagb == TAG_Valid)) + || ((taga == TW_Denormal) && (tagb == TW_Denormal))) { + if (denormal_operand() < 0) + return FPU_Exception; + + FPU_to_exp16(a, &x); + FPU_to_exp16(b, &y); + tag = FPU_u_div(&x, &y, dest, control_w, sign); + if (tag < 0) + return tag; + + FPU_settagi(deststnr, tag); + return tag; + } else if ((taga <= TW_Denormal) && (tagb <= TW_Denormal)) { + if (tagb != TAG_Zero) { + /* Want to find Zero/Valid */ + if (tagb == TW_Denormal) { + if (denormal_operand() < 0) + return FPU_Exception; + } + + /* The result is zero. */ + FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); + setsign(dest, sign); + return TAG_Zero; + } + /* We have an exception condition, either 0/0 or Valid/Zero. */ + if (taga == TAG_Zero) { + /* 0/0 */ + return arith_invalid(deststnr); + } + /* Valid/Zero */ + return FPU_divide_by_zero(deststnr, sign); + } + /* Must have infinities, NaNs, etc */ + else if ((taga == TW_NaN) || (tagb == TW_NaN)) { + if (flags & LOADED) + return real_2op_NaN((FPU_REG *) rm, flags & 0x0f, 0, + st0_ptr); + + if (flags & DEST_RM) { + int tag; + tag = FPU_gettag0(); + if (tag == TAG_Special) + tag = FPU_Special(st0_ptr); + return real_2op_NaN(st0_ptr, tag, rm, + (flags & REV) ? st0_ptr : &st(rm)); + } else { + int tag; + tag = FPU_gettagi(rm); + if (tag == TAG_Special) + tag = FPU_Special(&st(rm)); + return real_2op_NaN(&st(rm), tag, 0, + (flags & REV) ? st0_ptr : &st(rm)); + } + } else if (taga == TW_Infinity) { + if (tagb == TW_Infinity) { + /* infinity/infinity */ + return arith_invalid(deststnr); + } else { + /* tagb must be Valid or Zero */ + if ((tagb == TW_Denormal) && (denormal_operand() < 0)) + return FPU_Exception; + + /* Infinity divided by Zero or Valid does + not raise and exception, but returns Infinity */ + FPU_copy_to_regi(a, TAG_Special, deststnr); + setsign(dest, sign); + return taga; + } + } else if (tagb == TW_Infinity) { + if ((taga == TW_Denormal) && (denormal_operand() < 0)) + return FPU_Exception; + + /* The result is zero. */ + FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); + setsign(dest, sign); + return TAG_Zero; + } +#ifdef PARANOID + else { + EXCEPTION(EX_INTERNAL | 0x102); + return FPU_Exception; + } +#endif /* PARANOID */ + + return 0; +} |