numparser2.h

/*
 * libtu/numparser2.h
 *
 * Copyright (c) Tuomo Valkonen 1999-2000.
 * 
 * This file is distributed under the terms of the "Artistic License".
 * See the included file LICENSE for details.
 */

#define MAX_MANTISSA 10  /* should be enough for our needs */
#define ULONG_SIZE (sizeof(ulong)*8)

/*
 * Can handle quite big numbers (depends on MAX_MANTISSA). This is really
 * a crappy little hack (especially the generic (non-i386asm) mulby10
 * algorithm... hopefully it works...) but this'll do for now.
 */

enum{
	NPNUM_INT,
	NPNUM_FLOAT
};

typedef struct _NPNum{
	unsigned char nmantissa;
	int type;
	int base;
 	bool negative;
	ulong mantissa[MAX_MANTISSA];
	long exponent;
} NPNum;

#define NUM_INIT {0, 0, 0, 0, {0,}, 0}

#define ADD_EXP(NUM, X) (NUM)->exponent+=(X);

#if defined(__GNUG__) && defined(i386) && !defined(LIBTU_NP_NO_I386_ASM)
 #define LIBTU_NP_I386_ASM
#endif

static int npnum_mulbase_add(NPNum *num, long base, long v)
{
	long i, j;
	ulong overflow;
#ifndef LIBTU_NP_I386_ASM
	ulong val;
#endif
	
	for(i=num->nmantissa;i>=0;i--){
#ifdef LIBTU_NP_I386_ASM
		__asm__("mul %4\n"
				: "=a" (num->mantissa[i]), "=d" (overflow)
				: "0" (num->mantissa[i]), "1" (0), "q" (base)
				: "eax", "edx");
#else
		overflow=0;
		val=num->mantissa[i];
		
		if(val<ULONG_MAX/base){
			val*=base;
		}else if(val){
			ulong tmp=val;
			ulong old=val;
			for(j=0; j<base; j++){
				val+=tmp;
				if(val<=old)
					overflow++;
				old=val;
			}
		}
		num->mantissa[i]=val;
#endif
		if(overflow){
			if(i==num->nmantissa){
				if(num->nmantissa==MAX_MANTISSA)
					return E_TOKZ_TOOBIG;
				num->nmantissa++;
			}
			num->mantissa[i+1]+=overflow;
		}
	}
	num->mantissa[0]+=v;
	
	return 0;
}

#undef LIBTU_NP_I386_ASM


/* */


static bool is_end(int c)
{
	return ((c!='.' && ispunct(c)) || isspace(c) || iscntrl(c));
}


/* */


static int parse_exponent(NPNum *num, Tokenizer *tokz, int c)
{
	long exp=0;
	bool neg=FALSE;
	int err=0;
	
	c=GETCH();
	
	if(c=='-' || c=='+'){
		if(c=='-')
			neg=TRUE;
		c=GETCH();
	}
	
	for(; 1; c=GETCH()){
		if(isdigit(c)){
			exp*=10;
			exp+=c-'0';
		}else if(is_end(c)){
			UNGETCH(c);
			break;
		}else{
			err=E_TOKZ_NUMFMT;
		}
	}

	if(neg)
		exp*=-1;
	
	ADD_EXP(num, exp);
	
	return err;
}


static int parse_number(NPNum *num, Tokenizer *tokz, int c)
{
	int base=10;
	int dm=1;
	int err=0;
	int tmp;
	
	if(c=='-' || c=='+'){
		if(c=='-')
			num->negative=TRUE;
		c=GETCH();
		if(!isdigit(c))
			err=E_TOKZ_NUMFMT;
	}else if(c=='0'){
		dm=0;
		c=GETCH();
		if(c=='x' || c=='X'){
			base=16;
			c=GETCH();
		}else if(c=='b' || c=='B'){
			base=2;
			c=GETCH();
		}else if('0'<=c && c<='7'){
			base=7;
		}else{
			dm=2;
		}
	}
	
	num->base=base;
	
	for(; 1; c=GETCH()){
		if((c=='e' || c=='E') && dm!=0){
			if(dm<2){
				err=E_TOKZ_NUMFMT;
				continue;
			}
			tmp=parse_exponent(num, tokz, c);
			if(err==0)
				err=tmp;
			break;
		}
		
		if(isxdigit(c)){
			if('0'<=c && c<='9')
				c-='0';
			else if(isupper(c))
				c-='A'-10;
			else
				c-='a'-10;
			
			if(c>=base)
				err=E_TOKZ_NUMFMT;
			
			npnum_mulbase_add(num, base, c);
			
			if(dm==1)
				dm=2;
			else if(dm==3)
				ADD_EXP(num, -1);
			
			continue;
		}
		
		if(c=='.'){
			if(dm!=2)
				err=E_TOKZ_NUMFMT;
			else
				dm=3;
			continue;
		}
		
		if(is_end(c)){
			UNGETCH(c);
			break;
		}
		
		err=E_TOKZ_NUMFMT;
	}
	
	num->type=(num->exponent==0 ? NPNUM_INT : NPNUM_FLOAT);
	
	return err;
}