From 0f4594540afd60c63a116ca3ef549d7f8e43b41a Mon Sep 17 00:00:00 2001
From: "Evgeniy A. Dushistov" <dushistov@mail.ru>
Date: Fri, 13 Mar 2020 18:11:44 +0300
Subject: [PATCH] export packet size as constant

Usefull for SPI, where we need provide read buffer simultaneously
with write buffer
---
 ublox/src/ubx_packets.rs   | 4 +++-
 ublox_derive/src/output.rs | 6 ++++--
 ublox_derive/src/tests.rs  | 6 ++++--
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/ublox/src/ubx_packets.rs b/ublox/src/ubx_packets.rs
index 8611ed1..7b0ce63 100644
--- a/ublox/src/ubx_packets.rs
+++ b/ublox/src/ubx_packets.rs
@@ -94,6 +94,8 @@ pub struct UbxPacketRequest {
 }
 
 impl UbxPacketRequest {
+    pub const PACKET_LEN: usize = 8;
+
     #[inline]
     pub fn request_for<T: UbxPacketMeta>() -> Self {
         Self {
@@ -107,7 +109,7 @@ impl UbxPacketRequest {
     }
 
     #[inline]
-    pub fn to_packet_bytes(self) -> [u8; 8] {
+    pub fn to_packet_bytes(self) -> [u8; Self::PACKET_LEN] {
         let mut ret = [
             SYNC_CHAR_1,
             SYNC_CHAR_2,
diff --git a/ublox_derive/src/output.rs b/ublox_derive/src/output.rs
index 91df834..f82418d 100644
--- a/ublox_derive/src/output.rs
+++ b/ublox_derive/src/output.rs
@@ -245,9 +245,11 @@ pub fn generate_send_code_for_packet(pack_descr: &PackDesc) -> Vec<TokenStream>
         let packet_payload_size_u16 = u16::try_from(packet_payload_size).unwrap();
         ret.push(quote! {
             impl #payload_struct {
+                pub const PACKET_LEN: usize = #packet_size;
+
                 #[inline]
-                pub fn to_packet_bytes(self) -> [u8; #packet_size] {
-                    let mut ret = [0u8; #packet_size];
+                pub fn to_packet_bytes(self) -> [u8; Self::PACKET_LEN] {
+                    let mut ret = [0u8; Self::PACKET_LEN];
                     ret[0] = SYNC_CHAR_1;
                     ret[1] = SYNC_CHAR_2;
                     ret[2] = #main_name::CLASS;
diff --git a/ublox_derive/src/tests.rs b/ublox_derive/src/tests.rs
index ba767be..7fd741c 100644
--- a/ublox_derive/src/tests.rs
+++ b/ublox_derive/src/tests.rs
@@ -222,9 +222,11 @@ fn test_ubx_packet_send() {
                 pub a: u8,
             }
             impl TestBuilder {
+                pub const PACKET_LEN: usize = 17usize;
+
                 #[inline]
-                pub fn to_packet_bytes(self) -> [u8; 17usize] {
-                    let mut ret = [0u8; 17usize];
+                pub fn to_packet_bytes(self) -> [u8; Self::PACKET_LEN] {
+                    let mut ret = [0u8; Self::PACKET_LEN];
                     ret[0] = SYNC_CHAR_1;
                     ret[1] = SYNC_CHAR_2;
                     ret[2] = Test::CLASS;