From e4660abbc284b5a5402dc743a5519b2ba40e209e Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Sat, 25 Oct 2025 18:03:14 -0400
Subject: fix CAN ID format

---
 fw/can.c | 16 ++++++++--------
 fw/can.h |  4 ++--
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/fw/can.c b/fw/can.c
index a977a97..6adb423 100644
--- a/fw/can.c
+++ b/fw/can.c
@@ -241,10 +241,10 @@ static void
 packId(CanId *id, U8 sidh, U8 sidl, U8 eid8, U8 eid0) {
 	if (sidl & IDE) { // extended ID
 		id->isExt = true;
-		id->eid[0] = (U8)(sidh << 3u) | (U8)(sidl >> 5u); // sid[7:0]
-		id->eid[1] = (U8)(eid0 << 3u) | (U8)(sidh >> 5u); //eid[4:0], sid[10:8]
-		id->eid[2] = (U8)(eid8 << 3u) | (U8)(eid0 >> 5u); // eid[12:5]
-		id->eid[3] = (U8)((sidl & 0x3) << 3u) | (U8)(eid8 >> 5u); // eid[17:13]
+		id->eid[0u] = eid0; // id[7:0]
+		id->eid[1u] = eid8; // idi[15:8]
+		id->eid[2u] = (sidh & 0x7) | (sidl & 0x3) | (sidl >> 3u); // id[23:21], id[20:18], id[17:16]
+		id->eid[3u] = (sidh >> 3u); // id[28:24]
 	} else { // standard ID
 		id->isExt = false;
 		id->sid.lo = (U8)(sidh << 3u) | (U8)(sidl >> 5u); // sid[7:0]
@@ -296,10 +296,10 @@ canReadRxb1(CanFrame *frame) {
 static void
 writeId(const CanId *id, Reg sidh, Reg sidl, Reg eid8, Reg eid0) {
 	if (id->isExt) { // extended
-		write(sidh, (U8)(id->eid[1] << 5u) | (U8)(id->eid[0] >> 3u)); // sid[10:3]
-		write(sidl, (U8)(id->eid[0] << 5u) | IDE | (U8)((id->eid[3] >> 3u) & 0x03)); // sid[2:0], exide, eid[28:27]
-		write(eid8, (U8)(id->eid[3] << 5u) | (U8)(id->eid[2] >> 3u)); // eid[26:19]
-		write(eid0, (U8)(id->eid[2] << 5u) | (U8)(id->eid[1] >> 3u)); // eid[18:11]
+		write(eid0, id->eid[0u]); // id[7:0]
+		write(eid8, id->eid[1u]); // id[15:8]
+		write(sidl, ((id->eid[2u] << 3u) & 0xE0) | IDE | (id->eid[2u] & 0x3)); // id[20:18], IDE, id[17:16]
+		write(sidh, (U8)((id->eid[3u] & 0x1F) << 3u) | (id->eid[2u] >> 5u)); // id[28:24], id[23:21]
 	} else { // standard
 		write(sidh, (U8)(id->sid.hi << 5u) | (U8)(id->sid.lo >> 3u));
 		write(sidl, (U8) (id->sid.lo << 5u));
diff --git a/fw/can.h b/fw/can.h
index 196fb9f..206cb1d 100644
--- a/fw/can.h
+++ b/fw/can.h
@@ -41,8 +41,8 @@ typedef enum {
 typedef struct {
 	bool isExt; // is extended
 	union {
-		U16 sid; // 11-bit standard ID
-		U32 eid; // 29-bit extended ID
+		U16 sid; // 11-bit standard ID -- ID[28:18]
+		U32 eid; // 29-bit extended ID -- ID[28:0]
 	};
 } CanId;
 
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