Add precise decimal digit generation

1 files changed, 16 insertions, 4 deletions

diff --git a/src/decimal.h b/src/decimal.h
index eefc07ef..8575cd85 100644
--- a/src/decimal.h
+++ b/src/decimal.h
@@ -19,14 +19,26 @@
 
 #include <stdint.h>
 
+typedef struct {
+	unsigned count; ///< Number of digits
+	int      expt;  ///< Power of 10 exponent
+} SerdDecimalCount;
+
 /// Return the number of decimal digits required to represent `n`
 int
 serd_count_digits(uint64_t i);
 
-unsigned
-serd_double_int_digits(double abs);
+/**
+   Write significant decimal digits for `d` into `buf`.
+
+   Writes only significant digits, without any leading or trailing zeros.  The
+   actual number is given by the exponent in the return value.
 
-unsigned
-serd_decimals(double d, char* buf, unsigned frac_digits);
+   @param d The number to convert to decimal, must be finite and non-zero.
+   @param buf The output buffer at least `max_digits` long.
+   @param max_digits The maximum number of digits to write.
+*/
+SerdDecimalCount
+serd_decimals(double d, char* buf, unsigned max_digits);
 
 #endif // SERD_DECIMAL_H