Extract FLOAT_BIAS and DOUBLE_BIAS.

This slightly increases consistency (they're properties of the
IEEE representation, like the mantissa/exponent bits).
Also, they'll be needed for the "large fixed integer" codepaths
outside of f2d() and d2d().

ryu/d2s.c

@@ -236,16 +236,14 @@ typedef struct floating_decimal_64 {
 } floating_decimal_64;
 
 static inline floating_decimal_64 d2d(const uint64_t ieeeMantissa, const uint32_t ieeeExponent) {
-  const int32_t bias = (1u << (DOUBLE_EXPONENT_BITS - 1)) - 1;
-
   int32_t e2;
   uint64_t m2;
   if (ieeeExponent == 0) {
     // We subtract 2 so that the bounds computation has 2 additional bits.
-    e2 = 1 - bias - DOUBLE_MANTISSA_BITS - 2;
+    e2 = 1 - DOUBLE_BIAS - DOUBLE_MANTISSA_BITS - 2;
     m2 = ieeeMantissa;
   } else {
-    e2 = (int32_t) ieeeExponent - bias - DOUBLE_MANTISSA_BITS - 2;
+    e2 = (int32_t) ieeeExponent - DOUBLE_BIAS - DOUBLE_MANTISSA_BITS - 2;
     m2 = (1ull << DOUBLE_MANTISSA_BITS) | ieeeMantissa;
   }
   const bool even = (m2 & 1) == 0;

ryu/d2s.h

@@ -35,6 +35,7 @@ typedef __uint128_t uint128_t;
 
 #define DOUBLE_MANTISSA_BITS 52
 #define DOUBLE_EXPONENT_BITS 11
+#define DOUBLE_BIAS 1023
 
 #define DOUBLE_POW5_INV_BITCOUNT 122
 #define DOUBLE_POW5_BITCOUNT 121

ryu/f2s.c

@@ -36,6 +36,7 @@
 
 #define FLOAT_MANTISSA_BITS 23
 #define FLOAT_EXPONENT_BITS 8
+#define FLOAT_BIAS 127
 
 // This table is generated by PrintFloatLookupTable.
 #define FLOAT_POW5_INV_BITCOUNT 59
@@ -151,16 +152,14 @@ typedef struct floating_decimal_32 {
 } floating_decimal_32;
 
 static inline floating_decimal_32 f2d(const uint32_t ieeeMantissa, const uint32_t ieeeExponent) {
-  const int32_t bias = (1u << (FLOAT_EXPONENT_BITS - 1)) - 1;
-
   int32_t e2;
   uint32_t m2;
   if (ieeeExponent == 0) {
     // We subtract 2 so that the bounds computation has 2 additional bits.
-    e2 = 1 - bias - FLOAT_MANTISSA_BITS - 2;
+    e2 = 1 - FLOAT_BIAS - FLOAT_MANTISSA_BITS - 2;
     m2 = ieeeMantissa;
   } else {
-    e2 = (int32_t) ieeeExponent - bias - FLOAT_MANTISSA_BITS - 2;
+    e2 = (int32_t) ieeeExponent - FLOAT_BIAS - FLOAT_MANTISSA_BITS - 2;
     m2 = (1u << FLOAT_MANTISSA_BITS) | ieeeMantissa;
   }
   const bool even = (m2 & 1) == 0;