Rewrite with working async

lib/rt/number.h

@@ -1,8 +1,31 @@
-// The number natives: conversions between numbers and strings
+// Numbers: conversions between numbers and strings
 #pragma once
 
 #include "str.h"
 
+// JS's Number::toString
+string_t __rt_number_to_string(double x);
+
+// JS's ToNumber on a string
+double __rt_string_to_number(string_t s);
+
+#include <math.h>
+
+// JS's `x ** y`: C's pow, except that a NaN exponent always gives NaN, and so does
+// an infinite exponent when |x| is 1. C gives 1 for both
+static inline double __rt_pow(double x, double y) {
+    if (isnan(y) || (isinf(y) && fabs(x) == 1)) return NAN;
+    return pow(x, y);
+}
+
+// JS's ToInt32: the number modulo 2^32, as a signed int. NaN and the infinities are 0
+static inline int32_t __rt_to_int32(double x) {
+    if (!isfinite(x)) return 0;
+    double m = fmod(trunc(x), 4294967296.0);
+    if (m < 0) m += 4294967296.0;
+    return (int32_t)(uint32_t)m;
+}
+
 #ifdef JSRT_IMPLEMENTATION
 #include <math.h>
 #include <stdio.h>
@@ -11,10 +34,10 @@
 
 // JS's Number::toString: the fewest digits that give the number back. Plain
 // notation while the decimal point is within 21 places, else exponential
-string_t __native_number_to_string(double x) {
-    if (isnan(x)) return jsrt_string_lit("NaN");
-    if (isinf(x)) return jsrt_string_lit(x < 0 ? "-Infinity" : "Infinity");
-    if (x == 0) return jsrt_string_lit("0");
+string_t __rt_number_to_string(double x) {
+    if (isnan(x)) return __rt_string_lit("NaN");
+    if (isinf(x)) return __rt_string_lit(x < 0 ? "-Infinity" : "Infinity");
+    if (x == 0) return __rt_string_lit("0");
 
     // The fewest digits: buf is [-]d[.ddd]e±xx
     char buf[64];
@@ -61,19 +84,19 @@ string_t __native_number_to_string(double x) {
         sprintf(o, "%c%s%se%c%d", digits[0], n > 1 ? "." : "", digits + 1, e < 0 ? '-' : '+', abs(e));
     }
 
-    return jsrt_string_lit(out);
+    return __rt_string_lit(out);
 }
 
-string_t __native_number_to_fixed(double x, int32_t digits) {
+string_t __rt_number_to_fixed(double x, int32_t digits) {
     char buf[400];
     snprintf(buf, sizeof buf, "%.*f", digits, x);
-    return jsrt_string_lit(buf);
+    return __rt_string_lit(buf);
 }
 
 // JS's ToNumber on a string: a decimal number with whitespace around it, or
 // only whitespace, which is 0. Anything else is NaN
-double __native_string_to_number(string_t s) {
-    char *utf8 = jsrt_string_utf8(s);
+double __rt_string_to_number(string_t s) {
+    char *utf8 = __rt_string_utf8(s);
     char *start = utf8, *end;
 
     while (*start == ' ' || (*start >= '\t' && *start <= '\r')) start++;