output.c

unix环境下实现的cmm语言编译器

/*output.c:管理输出缓冲区，并进行格式化输出*/
#include "cmm.h"
#include <stdarg.h>
#include <unistd.h>
#include <limits.h>

static char *tokstr[] = {	/*记号对应的字符串*/
#define xx(a,b,c,d,e,f,g) g,
#define yy(a,b,c,d,e,f,g) g,
#include "token.h"
};

int outfd = 1;	/*输出文件的描述符，默认为标准输出*/
int errfd = 2;	/*错误输出文件的描述符，默认为标准出错*/
static int fd = 1;		/*内部缓冲区的索引。为0表示在临时缓冲区，主要用来
						 *为存储字符串做为临时缓冲区。为1表示在默认的输出缓冲区。
						 *为2时用于输出出错信息缓冲或其它输出缓冲*/

static char buf1[4 * 1024],buf2[512]; /*内部缓冲区*/
char *bp = buf1;
static struct io { /*文件高速缓冲结构*/
	int fd;			/*保存使用该缓冲区的文件描述符*/
	char *bp; 		/*缓冲区当前偏移指针*/
	char *buffer;	/*缓冲区起始地址*/
	char *limit;	/*缓冲区的结束地址*/
}iob[] = {
	{0,0,0,0},
	{1,buf1,buf1,buf1 + sizeof buf1},	
	{2,buf2,buf2,buf2 + sizeof buf2	}
},*io[] = {
	&iob[0],
	&iob[1],
	&iob[2]
};

static void vprint(char *fmt, va_list ap);
/*printtoken:输出当前记号*/
void printtoken(void)
{
	fprint(2,"'%s'",(t == ID || t == ICON 
					|| t == SCON || t == CCON) ? token: tokstr[t]);
}

/*outputInit:初始化输出高速缓存,设置默认的输出文件和出错输出文件*/
void outputInit(void)
{
	io[1]->fd = outfd;
	io[2]->fd = errfd;
}

/*outs:输出字符串s*/
void outs(char *s)
{
	char *p;
	assert(s);
	for(p = bp; (*p = *s++) != 0;p++)
		;
	bp = p;
	if(bp > io[fd]->limit)
		outflush();
}

/*outflush:清空缓冲区*/
void outflush(void)
{
	struct io *iop = io[fd];
	assert(fd);
	if(bp > iop->buffer)
		write(iop->fd, iop->buffer, bp - iop->buffer);
	bp = iop->bp = iop->buffer;
}

/*print:向输出文件输出格式化字符串fmt*/
void print(char *fmt,...)
{
	va_list ap;

	va_start(ap,fmt);
	vprint(fmt,ap);
	va_end(ap);
}

void fprint(int fd, char *fmt, ...)
{
	va_list ap;
	
	va_start(ap, fmt);
	vfprint(fd, fmt, ap);
	va_end(ap);
}

/*stringf:存储格式化字符串fmt*/
char *stringf(char *fmt, ...)
{
	char buf[_POSIX_ARG_MAX];
	va_list ap;

	va_start(ap, fmt);
	fd = 0;			/*使用0号缓冲区*/
	io[1]->bp = bp; /*保存当前输出的偏移*/
	bp = io[0]->bp = io[0]->buffer = buf;
	io[0]->limit = bp + sizeof buf;
	vprint(fmt,ap);
	*bp = 0;
	fd = 1; 		/*恢复使用1号缓冲区*/
	bp = io[1]->bp;
	return strings(buf);
}

/*vfprint:向文件f中输出格式化字符串fmt*/
void vfprint(int f, char *fmt,va_list ap)
{
	if(f == 1) /*当f为1时及使用标准输出，将使用1号缓冲区*/
		vprint(fmt, ap);
	else {
		fd = 2;
		io[2]->fd = 2 == f ? errfd:f;
		io[1]->bp = bp;
		bp = io[2]->bp;
		vprint(fmt,ap);
		outflush();
		bp = io[1]->bp;
		fd = 1;
	}
}

/*vprint:按格式化字符串fmt输出字符*/
static void vprint(char *fmt, va_list ap)
{
	char *s;
	for(; fmt && *fmt; fmt++) {
		if(*fmt == '%')
			switch(*++fmt){
			case 'd': {int n = va_arg(ap,int); /*将整形数字转换成字符串形式*/
				char buf[25];
				unsigned m;
				s = buf + sizeof buf;
				*--s = 0;
				if(n == INT_MIN)
					m = (unsigned)INT_MAX + 1U;
				else if(n < 0)
					m = -n;
				else 
					m = n;
				do 
					*--s = m % 10 + '0';
				while((m = m/10) != 0);
				if (n < 0)
					*--s = '-';	
				outs(s);	
				}break;
			case 'x': { unsigned n = va_arg(ap, unsigned);
				    char buf[25], *s = buf + sizeof buf;
				    *--s = 0;
				    do
				    	*--s = "0123456789abcdef"[n&0xf];
				    while ((n >>= 4) != 0);
				    outs(s);
				} break;
			case 'c': *bp++ = va_arg(ap, int); /*输出字符*/
				break;
			case 'k': /*输出记号*/
				{int tok = va_arg(ap, int);
				outs((tok == ID || tok == ICON || tok == CCON
				|| tok == SCON )? token:tokstr[tok]);	
				}break;
			case 's': /*输出字符串*/
				s = va_arg(ap, char *);
				if(s)
					outs(s);
				break;
			case 'S':{ /*输出定长度的字符串*/
				s = va_arg(ap, char *);
				int n = va_arg(ap, int);
				if(s)
					while(n-- >0)
						*bp++ = *s++;
				}break;
			case 't':{Type ty = va_arg(ap, Type); /*输出类型*/
				outtype(ty ? ty:voidtype);
				}break;
			case 'w':{Coordinate *p = va_arg(ap, Coordinate *); /*输出文件位置坐标*/
					if(p->file && *p->file)
						print("%s:",p->file);
					print("%d", p->y);
				}break;
			default:
				*bp++ = *fmt;
				break;
			}
		else if((*bp++ = *fmt) == '\n' && bp > io[fd]->limit) 
			outflush();
	}
}