minor but worthwhile optimization in printf: avoid expensive strspn

[musl] / src / stdio / vfprintf.c

diff --git a/src/stdio/vfprintf.c b/src/stdio/vfprintf.c
index b5001ff..d186d58 100644 (file)
--- a/src/stdio/vfprintf.c
+++ b/src/stdio/vfprintf.c
@@ -73,6 +73,8 @@ static const unsigned char states[]['z'-'A'+1] = {
        }, { /* 1: l-prefixed */
                S('d') = LONG, S('i') = LONG,
                S('o') = ULONG, S('u') = ULONG, S('x') = ULONG, S('X') = ULONG,
+               S('e') = DBL, S('f') = DBL, S('g') = DBL, S('a') = DBL,
+               S('E') = DBL, S('F') = DBL, S('G') = DBL, S('A') = DBL,
                S('c') = INT, S('s') = PTR, S('n') = PTR,
                S('l') = LLPRE,
        }, { /* 2: ll-prefixed */
@@ -294,7 +296,7 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
                e2-=sh;
        }
        while (e2<0) {
-               uint32_t carry=0, *z2;
+               uint32_t carry=0, *b;
                int sh=MIN(9,-e2);
                for (d=a; d<z; d++) {
                        uint32_t rm = *d & (1<<sh)-1;
@@ -304,8 +306,8 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
                if (!*a) a++;
                if (carry) *z++ = carry;
                /* Avoid (slow!) computation past requested precision */
-               z2 = ((t|32)=='f' ? r : a) + 2 + p/9;
-               z = MIN(z, z2);
+               b = (t|32)=='f' ? r : a;
+               if (z-b > 2+p/9) z = b+2+p/9;
                e2+=sh;
        }
 
@@ -317,7 +319,7 @@ static int fmt_fp(FILE *f, long double y, int w, int p, int fl, int t)
        if (j < 9*(z-r-1)) {
                uint32_t x;
                /* We avoid C's broken division of negative numbers */
-               d = r + 1 + (j+9*LDBL_MAX_EXP)/9 - LDBL_MAX_EXP;
+               d = r + 1 + ((j+9*LDBL_MAX_EXP)/9 - LDBL_MAX_EXP);
                j += 9*LDBL_MAX_EXP;
                j %= 9;
                for (i=10, j++; j<9; i*=10, j++);
@@ -428,7 +430,7 @@ static int getint(char **s) {
 static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg, int *nl_type)
 {
        char *a, *z, *s=(char *)fmt;
-       unsigned l10n=0, litpct, fl;
+       unsigned l10n=0, fl;
        int w, p;
        union arg arg;
        int argpos;
@@ -453,9 +455,7 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
 
                /* Handle literal text and %% format specifiers */
                for (a=s; *s && *s!='%'; s++);
-               litpct = strspn(s, "%")/2; /* Optimize %%%% runs */
-               z = s+litpct;
-               s += 2*litpct;
+               for (z=s; s[0]=='%' && s[1]=='%'; z++, s+=2);
                l = z-a;
                if (f) out(f, a, l);
                if (l) continue;
@@ -597,12 +597,12 @@ static int printf_core(FILE *f, const char *fmt, va_list *ap, union arg *nl_arg,
                        p = -1;
                case 'S':
                        ws = arg.p;
-                       for (i=0; *ws && (l=wctomb(mb, *ws++))>=0 && l<=0U+p-i; i+=l);
+                       for (i=l=0; i<0U+p && *ws && (l=wctomb(mb, *ws++))>=0 && l<=0U+p-i; i+=l);
                        if (l<0) return -1;
                        p = i;
                        pad(f, ' ', w, p, fl);
                        ws = arg.p;
-                       for (i=0; *ws && i+(l=wctomb(mb, *ws++))<=p; i+=l)
+                       for (i=0; i<0U+p && *ws && i+(l=wctomb(mb, *ws++))<=p; i+=l)
                                out(f, mb, l);
                        pad(f, ' ', w, p, fl^LEFT_ADJ);
                        l = w>p ? w : p;
@@ -650,8 +650,9 @@ int vfprintf(FILE *f, const char *fmt, va_list ap)
        FLOCK(f);
        if (!f->buf_size) {
                saved_buf = f->buf;
-               f->buf = internal_buf;
+               f->wpos = f->wbase = f->buf = internal_buf;
                f->buf_size = sizeof internal_buf;
+               f->wend = internal_buf + sizeof internal_buf;
        }
        ret = printf_core(f, fmt, &ap2, nl_arg, nl_type);
        if (saved_buf) {