11da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/*---------------------------------------------------------------------------+ 21da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | reg_mul.c | 31da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | | 41da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | Multiply one FPU_REG by another, put the result in a destination FPU_REG. | 51da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | | 61da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | Copyright (C) 1992,1993,1997 | 71da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | 81da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | E-mail billm@suburbia.net | 91da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | | 101da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | Returns the tag of the result if no exceptions or errors occurred. | 111da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | | 121da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds +---------------------------------------------------------------------------*/ 131da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 141da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/*---------------------------------------------------------------------------+ 151da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds | The destination may be any FPU_REG, including one of the source FPU_REGs. | 161da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds +---------------------------------------------------------------------------*/ 171da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 181da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include "fpu_emu.h" 191da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include "exception.h" 201da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include "reg_constant.h" 211da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include "fpu_system.h" 221da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 231da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/* 241da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds Multiply two registers to give a register result. 251da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds The sources are st(deststnr) and (b,tagb,signb). 261da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds The destination is st(deststnr). 271da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 281da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/* This routine must be called with non-empty source registers */ 291da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvaldsint FPU_mul(FPU_REG const *b, u_char tagb, int deststnr, int control_w) 301da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 313d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_REG *a = &st(deststnr); 323d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_REG *dest = a; 333d0d14f983b55a570b976976284df4c434af3223Ingo Molnar u_char taga = FPU_gettagi(deststnr); 343d0d14f983b55a570b976976284df4c434af3223Ingo Molnar u_char saved_sign = getsign(dest); 353d0d14f983b55a570b976976284df4c434af3223Ingo Molnar u_char sign = (getsign(a) ^ getsign(b)); 363d0d14f983b55a570b976976284df4c434af3223Ingo Molnar int tag; 371da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 383d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (!(taga | tagb)) { 393d0d14f983b55a570b976976284df4c434af3223Ingo Molnar /* Both regs Valid, this should be the most common case. */ 401da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 413d0d14f983b55a570b976976284df4c434af3223Ingo Molnar tag = 423d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_u_mul(a, b, dest, control_w, sign, 433d0d14f983b55a570b976976284df4c434af3223Ingo Molnar exponent(a) + exponent(b)); 443d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (tag < 0) { 453d0d14f983b55a570b976976284df4c434af3223Ingo Molnar setsign(dest, saved_sign); 463d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return tag; 473d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } 483d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_settagi(deststnr, tag); 493d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return tag; 501da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 511da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 523d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (taga == TAG_Special) 533d0d14f983b55a570b976976284df4c434af3223Ingo Molnar taga = FPU_Special(a); 543d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (tagb == TAG_Special) 553d0d14f983b55a570b976976284df4c434af3223Ingo Molnar tagb = FPU_Special(b); 561da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 573d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (((taga == TAG_Valid) && (tagb == TW_Denormal)) 581da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds || ((taga == TW_Denormal) && (tagb == TAG_Valid)) 593d0d14f983b55a570b976976284df4c434af3223Ingo Molnar || ((taga == TW_Denormal) && (tagb == TW_Denormal))) { 603d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_REG x, y; 613d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (denormal_operand() < 0) 623d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return FPU_Exception; 631da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 643d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_to_exp16(a, &x); 653d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_to_exp16(b, &y); 663d0d14f983b55a570b976976284df4c434af3223Ingo Molnar tag = FPU_u_mul(&x, &y, dest, control_w, sign, 673d0d14f983b55a570b976976284df4c434af3223Ingo Molnar exponent16(&x) + exponent16(&y)); 683d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (tag < 0) { 693d0d14f983b55a570b976976284df4c434af3223Ingo Molnar setsign(dest, saved_sign); 703d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return tag; 713d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } 723d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_settagi(deststnr, tag); 733d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return tag; 743d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } else if ((taga <= TW_Denormal) && (tagb <= TW_Denormal)) { 753d0d14f983b55a570b976976284df4c434af3223Ingo Molnar if (((tagb == TW_Denormal) || (taga == TW_Denormal)) 763d0d14f983b55a570b976976284df4c434af3223Ingo Molnar && (denormal_operand() < 0)) 773d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return FPU_Exception; 781da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 793d0d14f983b55a570b976976284df4c434af3223Ingo Molnar /* Must have either both arguments == zero, or 803d0d14f983b55a570b976976284df4c434af3223Ingo Molnar one valid and the other zero. 813d0d14f983b55a570b976976284df4c434af3223Ingo Molnar The result is therefore zero. */ 823d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr); 833d0d14f983b55a570b976976284df4c434af3223Ingo Molnar /* The 80486 book says that the answer is +0, but a real 843d0d14f983b55a570b976976284df4c434af3223Ingo Molnar 80486 behaves this way. 853d0d14f983b55a570b976976284df4c434af3223Ingo Molnar IEEE-754 apparently says it should be this way. */ 863d0d14f983b55a570b976976284df4c434af3223Ingo Molnar setsign(dest, sign); 873d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return TAG_Zero; 883d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } 893d0d14f983b55a570b976976284df4c434af3223Ingo Molnar /* Must have infinities, NaNs, etc */ 903d0d14f983b55a570b976976284df4c434af3223Ingo Molnar else if ((taga == TW_NaN) || (tagb == TW_NaN)) { 913d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return real_2op_NaN(b, tagb, deststnr, &st(0)); 923d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } else if (((taga == TW_Infinity) && (tagb == TAG_Zero)) 933d0d14f983b55a570b976976284df4c434af3223Ingo Molnar || ((tagb == TW_Infinity) && (taga == TAG_Zero))) { 943d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return arith_invalid(deststnr); /* Zero*Infinity is invalid */ 953d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } else if (((taga == TW_Denormal) || (tagb == TW_Denormal)) 963d0d14f983b55a570b976976284df4c434af3223Ingo Molnar && (denormal_operand() < 0)) { 973d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return FPU_Exception; 983d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } else if (taga == TW_Infinity) { 993d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_copy_to_regi(a, TAG_Special, deststnr); 1003d0d14f983b55a570b976976284df4c434af3223Ingo Molnar setsign(dest, sign); 1013d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return TAG_Special; 1023d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } else if (tagb == TW_Infinity) { 1033d0d14f983b55a570b976976284df4c434af3223Ingo Molnar FPU_copy_to_regi(b, TAG_Special, deststnr); 1043d0d14f983b55a570b976976284df4c434af3223Ingo Molnar setsign(dest, sign); 1053d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return TAG_Special; 1063d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } 1071da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#ifdef PARANOID 1083d0d14f983b55a570b976976284df4c434af3223Ingo Molnar else { 1093d0d14f983b55a570b976976284df4c434af3223Ingo Molnar EXCEPTION(EX_INTERNAL | 0x102); 1103d0d14f983b55a570b976976284df4c434af3223Ingo Molnar return FPU_Exception; 1113d0d14f983b55a570b976976284df4c434af3223Ingo Molnar } 1123d0d14f983b55a570b976976284df4c434af3223Ingo Molnar#endif /* PARANOID */ 1131da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1141da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds return 0; 1151da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 116