128 lines
2.9 KiB
C
128 lines
2.9 KiB
C
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/*---------------------------------------------------------------------------+
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| fpu_etc.c |
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| Implement a few FPU instructions. |
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| Copyright (C) 1992,1993,1994 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@vaxc.cc.monash.edu.au |
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+---------------------------------------------------------------------------*/
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#include "fpu_system.h"
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#include "exception.h"
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#include "fpu_emu.h"
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#include "status_w.h"
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#include "reg_constant.h"
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static void fchs(void)
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{
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if ( NOT_EMPTY_0 )
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{
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FPU_st0_ptr->sign ^= SIGN_POS^SIGN_NEG;
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clear_C1();
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}
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else
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stack_underflow();
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}
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static void fabs(void)
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{
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if ( FPU_st0_tag ^ TW_Empty )
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{
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FPU_st0_ptr->sign = SIGN_POS;
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clear_C1();
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}
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else
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stack_underflow();
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}
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static void ftst_(void)
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{
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switch (FPU_st0_tag)
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{
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case TW_Zero:
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setcc(SW_C3);
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break;
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case TW_Valid:
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if (FPU_st0_ptr->sign == SIGN_POS)
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setcc(0);
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else
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setcc(SW_C0);
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#ifdef DENORM_OPERAND
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if ( (FPU_st0_ptr->exp <= EXP_UNDER) && (denormal_operand()) )
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{
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#ifdef PECULIAR_486
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/* This is wierd! */
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if (FPU_st0_ptr->sign == SIGN_POS)
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setcc(SW_C3);
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#endif PECULIAR_486
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return;
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}
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#endif DENORM_OPERAND
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break;
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case TW_NaN:
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setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */
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EXCEPTION(EX_Invalid);
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break;
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case TW_Infinity:
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if (FPU_st0_ptr->sign == SIGN_POS)
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setcc(0);
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else
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setcc(SW_C0);
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break;
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case TW_Empty:
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setcc(SW_C0|SW_C2|SW_C3);
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EXCEPTION(EX_StackUnder);
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break;
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default:
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setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */
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EXCEPTION(EX_INTERNAL|0x14);
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break;
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}
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}
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static void fxam(void)
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{
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int c=0;
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switch (FPU_st0_tag)
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{
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case TW_Empty:
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c = SW_C3|SW_C0;
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break;
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case TW_Zero:
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c = SW_C3;
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break;
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case TW_Valid:
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/* This will need to be changed if TW_Denormal is ever used. */
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if ( FPU_st0_ptr->exp <= EXP_UNDER )
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c = SW_C2|SW_C3; /* Denormal */
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else
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c = SW_C2;
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break;
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case TW_NaN:
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c = SW_C0;
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break;
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case TW_Infinity:
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c = SW_C2|SW_C0;
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break;
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}
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if (FPU_st0_ptr->sign == SIGN_NEG)
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c |= SW_C1;
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setcc(c);
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}
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static FUNC const fp_etc_table[] = {
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fchs, fabs, FPU_illegal, FPU_illegal, ftst_, fxam, FPU_illegal, FPU_illegal
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};
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void fp_etc()
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{
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(fp_etc_table[FPU_rm])();
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}
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