int FPU_sub(int flags, int rm, int control_w) { FPU_REG const *a, *b; FPU_REG *dest; u_char taga, tagb, signa, signb, saved_sign, sign; int diff, tag = 0, expa, expb, deststnr; a = &st(0); taga = FPU_gettag0(); deststnr = 0; if (flags & LOADED) { b = (FPU_REG *) rm; tagb = flags & 0x0f; } else { b = &st(rm); tagb = FPU_gettagi(rm); if (flags & DEST_RM) deststnr = rm; } signa = getsign(a); signb = getsign(b); if (flags & REV) { signa ^= SIGN_NEG; signb ^= SIGN_NEG; } dest = &st(deststnr); saved_sign = getsign(dest); if (!(taga | tagb)) { expa = exponent(a); expb = exponent(b); valid_subtract: diff = expa - expb; if (!diff) { diff = a->sigh - b->sigh; if (!diff) { diff = a->sigl > b->sigl; if (!diff) diff = -(a->sigl < b->sigl); } } switch ((((int)signa) * 2 + signb) / SIGN_NEG) { case 0: case 3: if (diff > 0) { tag = FPU_u_sub(a, b, dest, control_w, signa, expa, expb); } else if (diff == 0) { FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); setsign(dest, ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG); return TAG_Zero; } else { sign = signa ^ SIGN_NEG; tag = FPU_u_sub(b, a, dest, control_w, sign, expb, expa); } break; case 1: tag = FPU_u_add(a, b, dest, control_w, SIGN_POS, expa, expb); break; case 2: tag = FPU_u_add(a, b, dest, control_w, SIGN_NEG, expa, expb); break; #ifdef PARANOID default: EXCEPTION(EX_INTERNAL | 0x111); return -1; #endif } if (tag < 0) { setsign(dest, saved_sign); 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))) { FPU_REG x, y; if (denormal_operand() < 0) return FPU_Exception; FPU_to_exp16(a, &x); FPU_to_exp16(b, &y); a = &x; b = &y; expa = exponent16(a); expb = exponent16(b); goto valid_subtract; } if ((taga == TW_NaN) || (tagb == TW_NaN)) { FPU_REG const *d1, *d2; if (flags & REV) { d1 = b; d2 = a; } else { d1 = a; d2 = b; } if (flags & LOADED) return real_2op_NaN(b, tagb, deststnr, d1); if (flags & DEST_RM) return real_2op_NaN(a, taga, deststnr, d2); else return real_2op_NaN(b, tagb, deststnr, d2); } return add_sub_specials(a, taga, signa, b, tagb, signb ^ SIGN_NEG, dest, deststnr, control_w); }
int FPU_add(FPU_REG const *b, u_char tagb, int deststnr, int control_w) { FPU_REG *a = &st(0); FPU_REG *dest = &st(deststnr); u_char signb = getsign(b); u_char taga = FPU_gettag0(); u_char signa = getsign(a); u_char saved_sign = getsign(dest); int diff, tag, expa, expb; if (!(taga | tagb)) { expa = exponent(a); expb = exponent(b); valid_add: if (!(signa ^ signb)) { tag = FPU_u_add(a, b, dest, control_w, signa, expa, expb); } else { diff = expa - expb; if (!diff) { diff = a->sigh - b->sigh; if (!diff) { diff = a->sigl > b->sigl; if (!diff) diff = -(a->sigl < b->sigl); } } if (diff > 0) { tag = FPU_u_sub(a, b, dest, control_w, signa, expa, expb); } else if (diff < 0) { tag = FPU_u_sub(b, a, dest, control_w, signb, expb, expa); } else { FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); setsign(dest, ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG); return TAG_Zero; } } if (tag < 0) { setsign(dest, saved_sign); 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))) { FPU_REG x, y; if (denormal_operand() < 0) return FPU_Exception; FPU_to_exp16(a, &x); FPU_to_exp16(b, &y); a = &x; b = &y; expa = exponent16(a); expb = exponent16(b); goto valid_add; } if ((taga == TW_NaN) || (tagb == TW_NaN)) { if (deststnr == 0) return real_2op_NaN(b, tagb, deststnr, a); else return real_2op_NaN(a, taga, deststnr, a); } return add_sub_specials(a, taga, signa, b, tagb, signb, dest, deststnr, control_w); }
/* 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; }
static int math_emulate(struct trapframe * tframe) { unsigned char FPU_modrm; unsigned short code; #ifdef LOOKAHEAD_LIMIT int lookahead_limit = LOOKAHEAD_LIMIT; #endif #ifdef PARANOID if (emulating) { printf("ERROR: wm-FPU-emu is not RE-ENTRANT!\n"); } REENTRANT_CHECK(ON); #endif /* PARANOID */ if ((((struct pcb *) curproc->p_addr)->pcb_flags & FP_SOFTFP) == 0) { finit(); control_word = __INITIAL_NPXCW__; ((struct pcb *) curproc->p_addr)->pcb_flags |= FP_SOFTFP; } FPU_info = tframe; FPU_ORIG_EIP = FPU_EIP; /* --pink-- */ if (FPU_CS != 0x001f) { printf("math_emulate: %x : %x\n", FPU_CS, FPU_EIP); panic("FPU emulation in kernel"); } #ifdef notyet /* We cannot handle emulation in v86-mode */ if (FPU_EFLAGS & 0x00020000) { FPU_ORIG_EIP = FPU_EIP; math_abort(FPU_info, SIGILL); } #endif FPU_lookahead = FPU_LOOKAHEAD; if (curproc->p_flag & P_TRACED) FPU_lookahead = 0; do_another_FPU_instruction: REENTRANT_CHECK(OFF); code = fuword((u_int *) FPU_EIP); REENTRANT_CHECK(ON); if ((code & 0xff) == 0x9b) { /* fwait */ if (status_word & SW_Summary) goto do_the_FPU_interrupt; else { FPU_EIP++; goto FPU_instruction_done; } } if (status_word & SW_Summary) { /* Ignore the error for now if the current instruction is a * no-wait control instruction */ /* The 80486 manual contradicts itself on this topic, so I use * the following list of such instructions until I can check * on a real 80486: fninit, fnstenv, fnsave, fnstsw, fnstenv, * fnclex. */ if (!((((code & 0xf803) == 0xe003) || /* fnclex, fninit, * fnstsw */ (((code & 0x3003) == 0x3001) && /* fnsave, fnstcw, * fnstenv, fnstsw */ ((code & 0xc000) != 0xc000))))) { /* This is a guess about what a real FPU might do to * this bit: */ /* status_word &= ~SW_Summary; ****/ /* We need to simulate the action of the kernel to FPU * interrupts here. Currently, the "real FPU" part of * the kernel (0.99.10) clears the exception flags, * sets the registers to empty, and passes information * back to the interrupted process via the cs selector * and operand selector, so we do the same. */ do_the_FPU_interrupt: cs_selector &= 0xffff0000; cs_selector |= (status_word & ~SW_Top) | ((top & 7) << SW_Top_Shift); operand_selector = tag_word(); status_word = 0; top = 0; { int r; for (r = 0; r < 8; r++) { regs[r].tag = TW_Empty; } } REENTRANT_CHECK(OFF); math_abort(SIGFPE); } } FPU_entry_eip = FPU_ORIG_EIP = FPU_EIP; if ((code & 0xff) == 0x66) { /* size prefix */ FPU_EIP++; REENTRANT_CHECK(OFF); code = fuword((u_int *) FPU_EIP); REENTRANT_CHECK(ON); } FPU_EIP += 2; FPU_modrm = code >> 8; FPU_rm = FPU_modrm & 7; if (FPU_modrm < 0300) { /* All of these instructions use the mod/rm byte to get a data * address */ get_address(FPU_modrm); if (!(code & 1)) { unsigned short status1 = status_word; FPU_st0_ptr = &st(0); FPU_st0_tag = FPU_st0_ptr->tag; /* Stack underflow has priority */ if (NOT_EMPTY_0) { switch ((code >> 1) & 3) { case 0: reg_load_single(); break; case 1: reg_load_int32(); break; case 2: reg_load_double(); break; case 3: reg_load_int16(); break; } /* No more access to user memory, it is safe * to use static data now */ FPU_st0_ptr = &st(0); FPU_st0_tag = FPU_st0_ptr->tag; /* NaN operands have the next priority. */ /* We have to delay looking at st(0) until * after loading the data, because that data * might contain an SNaN */ if ((FPU_st0_tag == TW_NaN) || (FPU_loaded_data.tag == TW_NaN)) { /* Restore the status word; we might * have loaded a denormal. */ status_word = status1; if ((FPU_modrm & 0x30) == 0x10) { /* fcom or fcomp */ EXCEPTION(EX_Invalid); setcc(SW_C3 | SW_C2 | SW_C0); if (FPU_modrm & 0x08) pop(); /* fcomp, so we pop. */ } else real_2op_NaN(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr); goto reg_mem_instr_done; } switch ((FPU_modrm >> 3) & 7) { case 0: /* fadd */ reg_add(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word); break; case 1: /* fmul */ reg_mul(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word); break; case 2: /* fcom */ compare_st_data(); break; case 3: /* fcomp */ compare_st_data(); pop(); break; case 4: /* fsub */ reg_sub(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word); break; case 5: /* fsubr */ reg_sub(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr, control_word); break; case 6: /* fdiv */ reg_div(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word); break; case 7: /* fdivr */ if (FPU_st0_tag == TW_Zero) status_word = status1; /* Undo any denorm tag, * zero-divide has * priority. */ reg_div(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr, control_word); break; } } else { if ((FPU_modrm & 0x30) == 0x10) {
int FPU_mul(FPU_REG const *b, u_char tagb, int deststnr, int control_w) { FPU_REG *a = &st(deststnr); FPU_REG *dest = a; u_char taga = FPU_gettagi(deststnr); u_char saved_sign = getsign(dest); u_char sign = (getsign(a) ^ getsign(b)); int tag; if (!(taga | tagb)) { tag = FPU_u_mul(a, b, dest, control_w, sign, exponent(a) + exponent(b)); if (tag < 0) { setsign(dest, saved_sign); 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))) { FPU_REG x, y; if (denormal_operand() < 0) return FPU_Exception; FPU_to_exp16(a, &x); FPU_to_exp16(b, &y); tag = FPU_u_mul(&x, &y, dest, control_w, sign, exponent16(&x) + exponent16(&y)); if (tag < 0) { setsign(dest, saved_sign); return tag; } FPU_settagi(deststnr, tag); return tag; } else if ((taga <= TW_Denormal) && (tagb <= TW_Denormal)) { if (((tagb == TW_Denormal) || (taga == TW_Denormal)) && (denormal_operand() < 0)) return FPU_Exception; FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); setsign(dest, sign); return TAG_Zero; } else if ((taga == TW_NaN) || (tagb == TW_NaN)) { return real_2op_NaN(b, tagb, deststnr, &st(0)); } else if (((taga == TW_Infinity) && (tagb == TAG_Zero)) || ((tagb == TW_Infinity) && (taga == TAG_Zero))) { return arith_invalid(deststnr); } else if (((taga == TW_Denormal) || (tagb == TW_Denormal)) && (denormal_operand() < 0)) { return FPU_Exception; } else if (taga == TW_Infinity) { FPU_copy_to_regi(a, TAG_Special, deststnr); setsign(dest, sign); return TAG_Special; } else if (tagb == TW_Infinity) { FPU_copy_to_regi(b, TAG_Special, deststnr); setsign(dest, sign); return TAG_Special; } #ifdef PARANOID else { EXCEPTION(EX_INTERNAL | 0x102); return FPU_Exception; } #endif return 0; }
void reg_add(FPU_REG *a, FPU_REG *b, FPU_REG *dest, int control_w) { int diff; if ( !(a->tag | b->tag) ) { /* Both registers are valid */ if (!(a->sign ^ b->sign)) { /* signs are the same */ reg_u_add(a, b, dest, control_w); dest->sign = a->sign; return; } /* The signs are different, so do a subtraction */ diff = a->exp - b->exp; if (!diff) { diff = a->sigh - b->sigh; /* Works only if ms bits are identical */ if (!diff) { diff = a->sigl > b->sigl; if (!diff) diff = -(a->sigl < b->sigl); } } if (diff > 0) { reg_u_sub(a, b, dest, control_w); dest->sign = a->sign; } else if ( diff == 0 ) { reg_move(&CONST_Z, dest); /* sign depends upon rounding mode */ dest->sign = ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG; } else { reg_u_sub(b, a, dest, control_w); dest->sign = b->sign; } return; } else { if ( (a->tag == TW_NaN) || (b->tag == TW_NaN) ) { real_2op_NaN(a, b, dest); return; } else if (a->tag == TW_Zero) { if (b->tag == TW_Zero) { char different_signs = a->sign ^ b->sign; /* Both are zero, result will be zero. */ reg_move(a, dest); if (different_signs) { /* Signs are different. */ /* Sign of answer depends upon rounding mode. */ dest->sign = ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG; } } else reg_move(b, dest); return; } else if (b->tag == TW_Zero) { reg_move(a, dest); return; } else if (a->tag == TW_Infinity) { if (b->tag != TW_Infinity) { reg_move(a, dest); return; } /* They are both + or - infinity */ if (a->sign == b->sign) { reg_move(a, dest); return; } reg_move(&CONST_QNaN, dest); /* inf - inf is undefined. */ return; } else if (b->tag == TW_Infinity) { reg_move(b, dest); return; } } #ifdef PARANOID EXCEPTION(EX_INTERNAL|0x101); #endif }
/* Subtract b from a. (a-b) -> dest */ void reg_sub(FPU_REG *a, FPU_REG *b, FPU_REG *dest, int control_w) { int diff; if ( !(a->tag | b->tag) ) { /* Both registers are valid */ diff = a->exp - b->exp; if (!diff) { diff = a->sigh - b->sigh; /* Works only if ms bits are identical */ if (!diff) { diff = a->sigl > b->sigl; if (!diff) diff = -(a->sigl < b->sigl); } } switch (a->sign*2 + b->sign) { case 0: /* P - P */ case 3: /* N - N */ if (diff > 0) { reg_u_sub(a, b, dest, control_w); dest->sign = a->sign; } else if ( diff == 0 ) { reg_move(&CONST_Z, dest); /* sign depends upon rounding mode */ dest->sign = ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG; } else { reg_u_sub(b, a, dest, control_w); dest->sign = a->sign ^ SIGN_POS^SIGN_NEG; } return; case 1: /* P - N */ reg_u_add(a, b, dest, control_w); dest->sign = SIGN_POS; return; case 2: /* N - P */ reg_u_add(a, b, dest, control_w); dest->sign = SIGN_NEG; return; } } else { if ( (a->tag == TW_NaN) || (b->tag == TW_NaN) ) { real_2op_NaN(a, b, dest); return; } else if (b->tag == TW_Zero) { if (a->tag == TW_Zero) { char same_signs = !(a->sign ^ b->sign); /* Both are zero, result will be zero. */ reg_move(a, dest); /* Answer for different signs. */ if (same_signs) { /* Sign depends upon rounding mode */ dest->sign = ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG; } } else reg_move(a, dest); return; } else if (a->tag == TW_Zero) { reg_move(b, dest); dest->sign ^= SIGN_POS^SIGN_NEG; return; } else if (a->tag == TW_Infinity) { if (b->tag != TW_Infinity) { reg_move(a, dest); return; } if (a->sign == b->sign) { reg_move(&CONST_QNaN, dest); return; } reg_move(a, dest); return; } else if (b->tag == TW_Infinity) { reg_move(b, dest); dest->sign ^= SIGN_POS^SIGN_NEG; return; } } #ifdef PARANOID EXCEPTION(EX_INTERNAL|0x110); #endif }
/* Operates on st(0) and st(n), or on st(0) and temporary data. The destination must be one of the source st(x). */ int FPU_add(FPU_REG const *b, u_char tagb, int deststnr, u16 control_w) { FPU_REG *a = &st(0); FPU_REG *dest = &st(deststnr); u_char signb = getsign(b); u_char taga = FPU_gettag0(); u_char signa = getsign(a); u_char saved_sign = getsign(dest); int diff, tag, expa, expb; if ( !(taga | tagb) ) { expa = exponent(a); expb = exponent(b); valid_add: /* Both registers are valid */ if (!(signa ^ signb)) { /* signs are the same */ tag = FPU_u_add(a, b, dest, control_w, signa, expa, expb); } else { /* The signs are different, so do a subtraction */ diff = expa - expb; if (!diff) { diff = a->sigh - b->sigh; /* This works only if the ms bits are identical. */ if (!diff) { diff = a->sigl > b->sigl; if (!diff) diff = -(a->sigl < b->sigl); } } if (diff > 0) { tag = FPU_u_sub(a, b, dest, control_w, signa, expa, expb); } else if ( diff < 0 ) { tag = FPU_u_sub(b, a, dest, control_w, signb, expb, expa); } else { FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); /* sign depends upon rounding mode */ setsign(dest, ((control_w & CW_RC) != RC_DOWN) ? SIGN_POS : SIGN_NEG); return TAG_Zero; } } if ( tag < 0 ) { setsign(dest, saved_sign); 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)) ) { FPU_REG x, y; if ( denormal_operand() < 0 ) return FPU_Exception; FPU_to_exp16(a, &x); FPU_to_exp16(b, &y); a = &x; b = &y; expa = exponent16(a); expb = exponent16(b); goto valid_add; } if ( (taga == TW_NaN) || (tagb == TW_NaN) ) { if ( deststnr == 0 ) return real_2op_NaN(b, tagb, deststnr, a); else return real_2op_NaN(a, taga, deststnr, a); } return add_sub_specials(a, taga, signa, b, tagb, signb, dest, deststnr, control_w); }
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)) { 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) { if (tagb == TW_Denormal) { if (denormal_operand() < 0) return FPU_Exception; } FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); setsign(dest, sign); return TAG_Zero; } if (taga == TAG_Zero) { return arith_invalid(deststnr); } return FPU_divide_by_zero(deststnr, sign); } 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) { return arith_invalid(deststnr); } else { if ((tagb == TW_Denormal) && (denormal_operand() < 0)) return FPU_Exception; 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; 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 return 0; }