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/*---------------------------------------------------------------------------+
| reg_constant.c |
| |
| All of the constant FPU_REGs |
| |
| Copyright (C) 1992,1993,1994,1996 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@jacobi.maths.monash.edu.au |
| |
| |
+---------------------------------------------------------------------------*/
#include "fpu_system.h"
#include "fpu_emu.h"
#include "status_w.h"
#include "reg_constant.h"
#include "control_w.h"
FPU_REG const CONST_1 = { SIGN_POS, TW_Valid, EXP_BIAS,
0x00000000, 0x80000000 };
FPU_REG const CONST_2 = { SIGN_POS, TW_Valid, EXP_BIAS+1,
0x00000000, 0x80000000 };
FPU_REG const CONST_HALF = { SIGN_POS, TW_Valid, EXP_BIAS-1,
0x00000000, 0x80000000 };
FPU_REG const CONST_L2T = { SIGN_POS, TW_Valid, EXP_BIAS+1,
0xcd1b8afe, 0xd49a784b };
FPU_REG const CONST_L2E = { SIGN_POS, TW_Valid, EXP_BIAS,
0x5c17f0bc, 0xb8aa3b29 };
FPU_REG const CONST_PI = { SIGN_POS, TW_Valid, EXP_BIAS+1,
0x2168c235, 0xc90fdaa2 };
FPU_REG const CONST_PI2 = { SIGN_POS, TW_Valid, EXP_BIAS,
0x2168c235, 0xc90fdaa2 };
FPU_REG const CONST_PI4 = { SIGN_POS, TW_Valid, EXP_BIAS-1,
0x2168c235, 0xc90fdaa2 };
FPU_REG const CONST_LG2 = { SIGN_POS, TW_Valid, EXP_BIAS-2,
0xfbcff799, 0x9a209a84 };
FPU_REG const CONST_LN2 = { SIGN_POS, TW_Valid, EXP_BIAS-1,
0xd1cf79ac, 0xb17217f7 };
/* Extra bits to take pi/2 to more than 128 bits precision. */
FPU_REG const CONST_PI2extra = { SIGN_NEG, TW_Valid, EXP_BIAS-66,
0xfc8f8cbb, 0xece675d1 };
/* Only the sign (and tag) is used in internal zeroes */
FPU_REG const CONST_Z = { SIGN_POS, TW_Zero, EXP_UNDER, 0x0, 0x0 };
/* Only the sign and significand (and tag) are used in internal NaNs */
/* The 80486 never generates one of these
FPU_REG const CONST_SNAN = { SIGN_POS, TW_NaN, EXP_OVER, 0x00000001, 0x80000000 };
*/
/* This is the real indefinite QNaN */
FPU_REG const CONST_QNaN = { SIGN_NEG, TW_NaN, EXP_OVER, 0x00000000, 0xC0000000 };
/* Only the sign (and tag) is used in internal infinities */
FPU_REG const CONST_INF = { SIGN_POS, TW_Infinity, EXP_OVER, 0x00000000, 0x80000000 };
static void fld_const(FPU_REG const *c, int adj)
{
FPU_REG *st_new_ptr;
if ( STACK_OVERFLOW )
{
stack_overflow();
return;
}
push();
reg_move(c, st_new_ptr);
st_new_ptr->sigl += adj; /* For all our fldxxx constants, we don't need to
borrow or carry. */
clear_C1();
}
/* A fast way to find out whether x is one of RC_DOWN or RC_CHOP
(and not one of RC_RND or RC_UP).
*/
#define DOWN_OR_CHOP(x) (x & RC_DOWN)
static void fld1(int rc)
{
fld_const(&CONST_1, 0);
}
static void fldl2t(int rc)
{
fld_const(&CONST_L2T, (rc == RC_UP) ? 1 : 0);
}
static void fldl2e(int rc)
{
fld_const(&CONST_L2E, DOWN_OR_CHOP(rc) ? -1 : 0);
}
static void fldpi(int rc)
{
fld_const(&CONST_PI, DOWN_OR_CHOP(rc) ? -1 : 0);
}
static void fldlg2(int rc)
{
fld_const(&CONST_LG2, DOWN_OR_CHOP(rc) ? -1 : 0);
}
static void fldln2(int rc)
{
fld_const(&CONST_LN2, DOWN_OR_CHOP(rc) ? -1 : 0);
}
static void fldz(int rc)
{
fld_const(&CONST_Z, 0);
}
typedef void (*FUNC_RC)(int);
static FUNC_RC constants_table[] = {
fld1, fldl2t, fldl2e, fldpi, fldlg2, fldln2, fldz, (FUNC_RC)FPU_illegal
};
void fconst(void)
{
(constants_table[FPU_rm])(control_word & CW_RC);
}
|
