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/***
*mantold.c - conversion of a decimal mantissa to _LDBL12** Copyright (c) 1991-2001, Microsoft Corporation. All rights reserved.**Purpose:* Conversion of a decimal mantissa into _LDBL12 format (i.e. long* double with two additional bytes of significand)**Revision History:* 7-17-91 GDP Initial version (ported from assembly)********************************************************************************/
#include <cv.h>
/***
*int _CALLTYPE5 __addl(u_long x, u_long y, u_long *sum) - u_long addition**Purpose: add two u_long numbers and return carry**Entry: u_long x, u_long y : the numbers to be added* u_long *sum : where to store the result**Exit: *sum receives the value of x+y* the value of the carry is returned**Exceptions:********************************************************************************/
int _CALLTYPE5 __addl(u_long x, u_long y, u_long *sum){ u_long r; int carry=0; r = x+y; if (r < x || r < y) carry++; *sum = r; return carry;}
/***
*void _CALLTYPE5 __add_12(_LDBL12 *x, _LDBL12 *y) - _LDBL12 addition**Purpose: add two _LDBL12 numbers. The numbers are added* as 12-byte integers. Overflow is ignored.**Entry: x,y: pointers to the operands**Exit: *x receives the sum**Exceptions:********************************************************************************/
void _CALLTYPE5 __add_12(_LDBL12 *x, _LDBL12 *y){ int c0,c1,c2; c0 = __addl(*UL_LO_12(x),*UL_LO_12(y),UL_LO_12(x)); if (c0) { c1 = __addl(*UL_MED_12(x),(u_long)1,UL_MED_12(x)); if (c1) { (*UL_HI_12(x))++; } } c2 = __addl(*UL_MED_12(x),*UL_MED_12(y),UL_MED_12(x)); if (c2) { (*UL_HI_12(x))++; } /* ignore next carry -- assume no overflow will occur */ (void) __addl(*UL_HI_12(x),*UL_HI_12(y),UL_HI_12(x));}
/***
*void _CALLTYPE5 __shl_12(_LDBL12 *x) - _LDBL12 shift left*void _CALLTYPE5 __shr_12(_LDBL12 *x) - _LDBL12 shift right**Purpose: Shift a _LDBL12 number one bit to the left (right). The number* is shifted as a 12-byte integer. The MSB is lost.**Entry: x: a pointer to the operand**Exit: *x is shifted one bit to the left (or right)**Exceptions:********************************************************************************/
void _CALLTYPE5 __shl_12(_LDBL12 *p){ u_long c0,c1;
c0 = *UL_LO_12(p) & MSB_ULONG ? 1: 0; c1 = *UL_MED_12(p) & MSB_ULONG ? 1: 0; *UL_LO_12(p) <<= 1; *UL_MED_12(p) = *UL_MED_12(p)<<1 | c0; *UL_HI_12(p) = *UL_HI_12(p)<<1 | c1;}
void _CALLTYPE5 __shr_12(_LDBL12 *p){ u_long c2,c1; c2 = *UL_HI_12(p) & 0x1 ? MSB_ULONG: 0; c1 = *UL_MED_12(p) & 0x1 ? MSB_ULONG: 0; *UL_HI_12(p) >>= 1; *UL_MED_12(p) = *UL_MED_12(p)>>1 | c2; *UL_LO_12(p) = *UL_LO_12(p)>>1 | c1;}
/***
*void _CALLTYPE5 __mtold12(char *manptr,unsigned manlen,_LDBL12 *ld12) -* convert a mantissa into a _LDBL12**Purpose: convert a mantissa into a _LDBL12. The mantissa is* in the form of an array of manlen BCD digits and is* considered to be an integer.**Entry: manptr: the array containing the packed BCD digits of the mantissa* manlen: the size of the array* ld12: a pointer to the long double where the result will be stored**Exit:* ld12 gets the result of the conversion**Exceptions:********************************************************************************/
void _CALLTYPE5 __mtold12(char *manptr, unsigned manlen, _LDBL12 *ld12){ _LDBL12 tmp; u_short expn = LD_BIASM1+80;
*UL_LO_12(ld12) = 0; *UL_MED_12(ld12) = 0; *UL_HI_12(ld12) = 0; for (;manlen>0;manlen--,manptr++){ tmp = *ld12; __shl_12(ld12); __shl_12(ld12); __add_12(ld12,&tmp); __shl_12(ld12); /* multiply by 10 */ *UL_LO_12(&tmp) = (u_long)*manptr; *UL_MED_12(&tmp) = 0; *UL_HI_12(&tmp) = 0; __add_12(ld12,&tmp); }
/* normalize mantissa -- first shift word by word */ while (*UL_HI_12(ld12) == 0) { *UL_HI_12(ld12) = *UL_MED_12(ld12) >> 16; *UL_MED_12(ld12) = *UL_MED_12(ld12) << 16 | *UL_LO_12(ld12) >> 16; (*UL_LO_12(ld12)) <<= 16; expn -= 16; } while ((*UL_HI_12(ld12) & 0x8000) == 0) { __shl_12(ld12); expn--; } *U_EXP_12(ld12) = expn;}
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