74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
#include <ieee.h>
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#define E IEEE_E
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#define M IEEE_M
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#define EXONE IEEE_EXONE
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// one of the many possible NaNs,
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// the one produced by the base converter
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const eNE ieee_nan { 0, 0, 0, 0, 0xc000, 0xffff };
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int idaapi realcvt(void *m, eNE e, unsigned short swt)
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{
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eNI x;
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long exp;
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unsigned short r, msk, *p = (unsigned short *)m;
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switch(swt) {
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case 1: // in float
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case 0: // in trunc. float
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case 3: // in double
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ecleaz(x);
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x[0] = ((r = *p) & 0x8000) ? 0xffff : 0; /* fill in our sign */
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if(!(r &= (0377 << 7))) {
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if ( x[0] ) // negative and zero exponent = Undefined -> transformed to NaN
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{
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memcpy(e, ieee_nan, sizeof(eNE));
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break;
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}
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// complain on dirty zero
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for(msk = 0x7fff, r = swt + 1; r; r--, msk = 0xffff)
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if(*p++ & msk) return(-3); // signed zero accepted
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} else {
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x[E] = (r >> 7) + (EXONE - 0201); /* DEC exponent offset */
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x[M] = (*p++ & 0177) | 0200; /* now do the high order mantissa */
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if(swt) memcpy(&x[M+1], p, swt*sizeof(unsigned short));
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eshift(x, -8); /* shift our mantissa down 8 bits */
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}
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if(e) emovo(x, e); // convert to IEEE format
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break;
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case 011: // out float
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case 010: // out trunc. float
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case 013: // out double
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emovi(e, x);
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r = swt & 3;
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if(!x[E]) goto clear;
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if ( x[E] == E_SPECIAL_EXP )
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{
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// all of NaN, +/-Inf transformed to "Undefined value"
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x[0] = 0xffff;
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x[E] = 0;
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goto clear;
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}
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exp = (long )x[E] - (EXONE - 0201);
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if(!emdnorm(x, 0, 0, exp, 56) || x[E] >= 0377)
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return REAL_ERROR_RANGE; // overfloat
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if(!x[E]) {
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clear:
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memset(p, 0, (r + 1)*sizeof(unsigned short));
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if(x[0]) *p = 0x8000; // signed zero accepted
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} else {
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*p = (x[0] ? 0100000 : 0) | (x[E] << 7); /* sign & exp */
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eshift(x, 8);
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*p++ |= (x[M] & 0177);
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if(r) memcpy(p, &x[M+1], r*sizeof(unsigned short));
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}
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break;
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default:
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return REAL_ERROR_FORMAT;
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}
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return 0;
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}
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