/* (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands. See the copyright notice in the ACK home directory, in the file "Copyright". */ /* $Header: /cvsup/minix/src/lib/float/extend.c,v 1.1.1.1 2005/04/21 14:56:10 beng Exp $ */ /* CONVERTS FLOATING POINT TO EXTENDED FORMAT Two sizes of FLOATING Point are known: SINGLE and DOUBLE */ /********************************************************/ /* It is not required to normalize in extended format, but it has been chosen to do so. Extended Format is as follows (at exit): ->sign S000 0000 | 0000 0000 ->exp 0EEE EEEE | EEEE EEEE ->m1 LFFF FFFF | FFFF FFFF FFFF FFFF | FFFF FFFF ->m2 FFFF FFFF | FFFF FFFF FFFF F000 | 0000 0000 */ /********************************************************/ #include "FP_bias.h" #include "FP_shift.h" #include "FP_types.h" #include "get_put.h" /********************************************************/ void extend(from,to,size) unsigned long *from; EXTEND *to; int size; { register char *cpt1; unsigned long tmp; int leadbit = 0; cpt1 = (char *) from; #if FL_MSL_AT_LOW_ADDRESS #if FL_MSW_AT_LOW_ADDRESS to->exp = uget2(cpt1); #else to->exp = uget2(cpt1+2); #endif #else #if FL_MSW_AT_LOW_ADDRESS to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 4 : 0)); #else to->exp = uget2(cpt1+(size == sizeof(DOUBLE) ? 6 : 2)); #endif #endif to->sign = (to->exp & 0x8000); /* set sign bit */ to->exp ^= to->sign; if (size == sizeof(DOUBLE)) to->exp >>= DBL_EXPSHIFT; else to->exp >>= SGL_EXPSHIFT; if (to->exp > 0) leadbit++; /* will set Lead bit later */ else to->exp++; if (size == sizeof(DOUBLE)) { #if FL_MSL_AT_LOW_ADDRESS to->m1 = get4(cpt1); cpt1 += 4; tmp = get4(cpt1); #else tmp = get4(cpt1); cpt1 += 4; to->m1 = get4(cpt1); #endif if (to->exp == 1 && to->m1 == 0 && tmp == 0) { to->exp = 0; to->sign = 0; to->m1 = 0; to->m2 = 0; return; } to->m1 <<= DBL_M1LEFT; /* shift */ to->exp -= DBL_BIAS; /* remove bias */ to->m1 |= (tmp>>DBL_RPACK); /* plus 10 == 32 */ to->m2 = (tmp<m1 = get4(cpt1); to->m1 <<= SGL_M1LEFT; /* shift */ if (to->exp == 1 && to->m1 == 0) { to->exp = 0; to->sign = 0; to->m1 = 0; to->m2 = 0; return; } to->exp -= SGL_BIAS; /* remove bias */ to->m2 = 0L; } to->m1 |= NORMBIT; /* set bit L */ if (leadbit == 0) { /* set or clear Leading Bit */ to->m1 &= ~NORMBIT; /* clear bit L */ nrm_ext(to); /* and normalize */ } }