wire: Implement fromwire/towire_double.

wire/fromwire.c

@@ -82,6 +82,11 @@ u64 fromwire_u64(const u8 **cursor, size_t *max)
 	return be64_to_cpu(ret);
 }
 
+void fromwire_double(const u8 **cursor, size_t *max, double *ret)
+{
+	fromwire(cursor, max, ret, sizeof(*ret));
+}
+
 bool fromwire_bool(const u8 **cursor, size_t *max)
 {
 	u8 ret;

wire/towire.c

@@ -39,6 +39,11 @@ void towire_u64(u8 **pptr, u64 v)
 	towire(pptr, &l, sizeof(l));
 }
 
+void towire_double(u8 **pptr, const double *v)
+{
+	towire(pptr, v, sizeof(*v));
+}
+
 void towire_bool(u8 **pptr, bool v)
 {
 	u8 val = v;

wire/wire.h

@@ -52,6 +52,7 @@ void towire_u8(u8 **pptr, u8 v);
 void towire_u16(u8 **pptr, u16 v);
 void towire_u32(u8 **pptr, u32 v);
 void towire_u64(u8 **pptr, u64 v);
+void towire_double(u8 **pptr, const double *v);
 void towire_pad(u8 **pptr, size_t num);
 void towire_bool(u8 **pptr, bool v);
 
@@ -65,6 +66,7 @@ u8 fromwire_u8(const u8 **cursor, size_t *max);
 u16 fromwire_u16(const u8 **cursor, size_t *max);
 u32 fromwire_u32(const u8 **cursor, size_t *max);
 u64 fromwire_u64(const u8 **cursor, size_t *max);
+void fromwire_double(const u8 **cursor, size_t *max, double *v);
 bool fromwire_bool(const u8 **cursor, size_t *max);
 void fromwire_secret(const u8 **cursor, size_t *max, struct secret *secret);
 void fromwire_privkey(const u8 **cursor, size_t *max, struct privkey *privkey);