use fast version of the int reading code for the high-order digits too

[musl] / src / internal / intparse.c

diff --git a/src/internal/intparse.c b/src/internal/intparse.c
index fd403b5..fba38c0 100644 (file)
--- a/src/internal/intparse.c
+++ b/src/internal/intparse.c
@@ -25,12 +25,12 @@ static const unsigned char digits[] = {
 };
 
 #define SLIM (UINT_MAX/36-1)
-#define LLIM (UINTMAX_MAX/36-1)
 
 int __intparse(struct intparse *v, const void *buf, size_t n)
 {
        const unsigned char *s = buf;
        int d, b = v->base;
+       uintmax_t llim;
 
        v->cnt += n;
        for (; n; n--, s++) switch (v->state) {
@@ -70,6 +70,8 @@ int __intparse(struct intparse *v, const void *buf, size_t n)
                        for (; n && *s-'0'<10U && v->small<=SLIM; n--, s++)
                                v->small = v->small * 10 + (*s-'0');
                } else if ((b&-b) == b) {
+                       /* Compute bitshift for power-of-two bases
+                        * using a De Bruijn B(2,3) sequence. */
                        int bs = "\0\1\2\4\7\3\6\5"[(0x17*b)>>5&7];
                        for (; n && (d=digits[*s])<b && v->small<=SLIM; n--, s++)
                                v->small = (v->small<<bs) + d;
@@ -81,16 +83,22 @@ int __intparse(struct intparse *v, const void *buf, size_t n)
                v->state++;
                v->val = v->small;
        case 5:
-               for (; n && (d=digits[*s])<b && v->val<=LLIM; n--, s++)
-                       v->val = v->val * b + d;
+               if (b==10) {
+                       for (; n && *s-'0'<10U && v->val<=UINTMAX_MAX/10 && (*s-'0')<=UINTMAX_MAX-10*v->val; n--, s++)
+                               v->val = v->val * 10 + (*s-'0');
+               } else if ((b&-b) == b) {
+                       int bs = "\0\1\2\4\7\3\6\5"[(0x17*b)>>5&7];
+                       llim = UINTMAX_MAX>>bs;
+                       for (; n && (d=digits[*s])<b && v->val<=llim; n--, s++)
+                               v->val = (v->val<<bs) + d;
+               } else {
+                       llim = UINTMAX_MAX/b;
+                       for (; n && (d=digits[*s])<b && v->val<=llim && d<=UINTMAX_MAX-b*v->val; n--, s++)
+                               v->val = v->val * b + d;
+               }
                if (!n) return 1;
                if (d >= b) goto finished;
-               if (v->val < (UINTMAX_MAX-d)/b)
-                       v->val = v->val * b + d;
-               else
-                       v->err = ERANGE;
                v->state++;
-               n--; s++;
        case 6:
                if (n && digits[*s]<b) {
                        v->err = ERANGE;