Added TCMalloc and JEMalloc projects

BeefRT/JEMalloc/src/fxp.c

@@ -0,0 +1,124 @@
+#include "jemalloc/internal/jemalloc_preamble.h"
+#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/fxp.h"
+
+static bool
+fxp_isdigit(char c) {
+	return '0' <= c && c <= '9';
+}
+
+bool
+fxp_parse(fxp_t *result, const char *str, char **end) {
+	/*
+	 * Using malloc_strtoumax in this method isn't as handy as you might
+	 * expect (I tried). In the fractional part, significant leading zeros
+	 * mean that you still need to do your own parsing, now with trickier
+	 * math.  In the integer part, the casting (uintmax_t to uint32_t)
+	 * forces more reasoning about bounds than just checking for overflow as
+	 * we parse.
+	 */
+	uint32_t integer_part = 0;
+
+	const char *cur = str;
+
+	/* The string must start with a digit or a decimal point. */
+	if (*cur != '.' && !fxp_isdigit(*cur)) {
+		return true;
+	}
+
+	while ('0' <= *cur && *cur <= '9') {
+		integer_part *= 10;
+		integer_part += *cur - '0';
+		if (integer_part >= (1U << 16)) {
+			return true;
+		}
+		cur++;
+	}
+
+	/*
+	 * We've parsed all digits at the beginning of the string, without
+	 * overflow.  Either we're done, or there's a fractional part.
+	 */
+	if (*cur != '.') {
+		*result = (integer_part << 16);
+		if (end != NULL) {
+			*end = (char *)cur;
+		}
+		return false;
+	}
+
+	/* There's a fractional part. */
+	cur++;
+	if (!fxp_isdigit(*cur)) {
+		/* Shouldn't end on the decimal point. */
+		return true;
+	}
+
+	/*
+	 * We use a lot of precision for the fractional part, even though we'll
+	 * discard most of it; this lets us get exact values for the important
+	 * special case where the denominator is a small power of 2 (for
+	 * instance, 1/512 == 0.001953125 is exactly representable even with
+	 * only 16 bits of fractional precision).  We need to left-shift by 16
+	 * before dividing so we pick the number of digits to be
+	 * floor(log(2**48)) = 14.
+	 */
+	uint64_t fractional_part = 0;
+	uint64_t frac_div = 1;
+	for (int i = 0; i < FXP_FRACTIONAL_PART_DIGITS; i++) {
+		fractional_part *= 10;
+		frac_div *= 10;
+		if (fxp_isdigit(*cur)) {
+			fractional_part += *cur - '0';
+			cur++;
+		}
+	}
+	/*
+	 * We only parse the first maxdigits characters, but we can still ignore
+	 * any digits after that.
+	 */
+	while (fxp_isdigit(*cur)) {
+		cur++;
+	}
+
+	assert(fractional_part < frac_div);
+	uint32_t fractional_repr = (uint32_t)(
+	    (fractional_part << 16) / frac_div);
+
+	/* Success! */
+	*result = (integer_part << 16) + fractional_repr;
+	if (end != NULL) {
+		*end = (char *)cur;
+	}
+	return false;
+}
+
+void
+fxp_print(fxp_t a, char buf[FXP_BUF_SIZE]) {
+	uint32_t integer_part = fxp_round_down(a);
+	uint32_t fractional_part = (a & ((1U << 16) - 1));
+
+	int leading_fraction_zeros = 0;
+	uint64_t fraction_digits = fractional_part;
+	for (int i = 0; i < FXP_FRACTIONAL_PART_DIGITS; i++) {
+		if (fraction_digits < (1U << 16)
+		    && fraction_digits * 10 >= (1U << 16)) {
+			leading_fraction_zeros = i;
+		}
+		fraction_digits *= 10;
+	}
+	fraction_digits >>= 16;
+	while (fraction_digits > 0 && fraction_digits % 10 == 0) {
+		fraction_digits /= 10;
+	}
+
+	size_t printed = malloc_snprintf(buf, FXP_BUF_SIZE, "%"FMTu32".",
+	    integer_part);
+	for (int i = 0; i < leading_fraction_zeros; i++) {
+		buf[printed] = '0';
+		printed++;
+	}
+	malloc_snprintf(&buf[printed], FXP_BUF_SIZE - printed, "%"FMTu64,
+	    fraction_digits);
+}