144 lines
3.2 KiB
C
144 lines
3.2 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) 1992,1993,1994,1997 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@suburbia.net |
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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(FPU_REG *st0_ptr, u_char st0tag)
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{
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if ( st0tag ^ TAG_Empty )
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{
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signbyte(st0_ptr) ^= SIGN_NEG;
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clear_C1();
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}
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else
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FPU_stack_underflow();
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}
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static void fabs(FPU_REG *st0_ptr, u_char st0tag)
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{
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if ( st0tag ^ TAG_Empty )
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{
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setpositive(st0_ptr);
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clear_C1();
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}
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else
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FPU_stack_underflow();
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}
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static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
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{
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switch (st0tag)
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{
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case TAG_Zero:
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setcc(SW_C3);
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break;
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case TAG_Valid:
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if (getsign(st0_ptr) == 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 TAG_Special:
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switch ( FPU_Special(st0_ptr) )
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{
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case TW_Denormal:
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if (getsign(st0_ptr) == SIGN_POS)
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setcc(0);
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else
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setcc(SW_C0);
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if ( denormal_operand() < 0 )
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{
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#ifdef PECULIAR_486
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/* This is weird! */
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if (getsign(st0_ptr) == 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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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 (getsign(st0_ptr) == 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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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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break;
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case TAG_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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}
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}
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static void fxam(FPU_REG *st0_ptr, u_char st0tag)
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{
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int c = 0;
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switch (st0tag)
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{
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case TAG_Empty:
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c = SW_C3|SW_C0;
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break;
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case TAG_Zero:
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c = SW_C3;
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break;
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case TAG_Valid:
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c = SW_C2;
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break;
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case TAG_Special:
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switch ( FPU_Special(st0_ptr) )
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{
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case TW_Denormal:
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c = SW_C2|SW_C3; /* Denormal */
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break;
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case TW_NaN:
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/* We also use NaN for unsupported types. */
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if ( (st0_ptr->sigh & 0x80000000) && (exponent(st0_ptr) == EXP_OVER) )
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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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}
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if ( getsign(st0_ptr) == 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_ST0 const fp_etc_table[] = {
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fchs, fabs, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal,
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ftst_, fxam, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal
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};
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void FPU_etc(void)
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{
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(fp_etc_table[FPU_rm])(&st(0), FPU_gettag0());
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}
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