From acaaeea450848bf951abf4789b1d2f7700f3d7eb Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Tue, 16 Jan 2024 15:32:43 +0100
Subject: [PATCH] picopass uses a different CRC algo

---
 armsrc/iso14443b.c | 9 ++++++++-
 armsrc/iso14443b.h | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index 1c9e94983..3df38098e 100644
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -2643,7 +2643,14 @@ void SendRawCommand14443B(iso14b_raw_cmd_t *p) {
     if ((p->flags & ISO14B_RAW) == ISO14B_RAW) {
 
         if (((p->flags & ISO14B_APPEND_CRC) == ISO14B_APPEND_CRC) && (p->rawlen)) {
-            AddCrc14B(p->raw, p->rawlen);
+
+            // Picopass uses different CRC algo
+            // it also excludes the first instruction byte
+            if ((p->flags & ISO14B_SELECT_PICOPASS) == ISO14B_SELECT_PICOPASS) {
+                AddCrc15(p->raw + 1, p->rawlen - 1);
+            } else {
+                AddCrc14B(p->raw, p->rawlen);
+            }
             p->rawlen += 2;
         }
 
diff --git a/armsrc/iso14443b.h b/armsrc/iso14443b.h
index bf0ac0bc6..83f617831 100644
--- a/armsrc/iso14443b.h
+++ b/armsrc/iso14443b.h
@@ -34,6 +34,10 @@
 # define AddCrc14B(data, len) compute_crc(CRC_14443_B, (data), (len), (data)+(len), (data)+(len)+1)
 #endif
 
+#ifndef AddCrc15
+#define AddCrc15(data, len) compute_crc(CRC_ICLASS, (data), (len), (data)+(len), (data)+(len)+1)
+#endif
+
 void iso14443b_setup(void);
 int iso14443b_apdu(uint8_t const *msg, size_t msg_len, bool send_chaining, void *rxdata, uint16_t rxmaxlen, uint8_t *res, uint16_t *responselen);