From 15769aa7329789e4a996321f0b7897949c230e07 Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Tue, 20 Jun 2023 00:45:35 +0200
Subject: Implement basic tag detection using reader_yhy

---
 reader.c     | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 reader_yhy.c | 21 +++++++++++++++-
 2 files changed, 96 insertions(+), 4 deletions(-)

diff --git a/reader.c b/reader.c
index bcfd28b..196d556 100644
--- a/reader.c
+++ b/reader.c
@@ -3,17 +3,29 @@
 #include <dlfcn.h>
 #include <sys/timerfd.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "nfcommander.h"
 #include "reader.h"
 #include "config.h"
 
 #define MAX_PLUGIN_PATH NAME_MAX
+#define DEFAULT_POLL_TIMEOUT 1000
+#define MAX_TAGS 5
+
+#define FLAG_CORE_NOTIFIED 1
+#define FLAG_ACTIVE 2
+#define FLAG_UNPROGRAMMED 4
+
 static void* reader_module = NULL;
 static reader_plugin_handle reader_backend_handle = NULL;
 static reader_plugin_scan reader_backend_scan = NULL;
 
 static int timer_fd = -1;
+static struct {
+	uint8_t flags;
+	nfc_tag_info_t info;
+} tags[MAX_TAGS] = { 0 };
 
 static int reader_init_backend(){
 	char plugin[MAX_PLUGIN_PATH] = "";
@@ -47,7 +59,7 @@ static int reader_init_backend(){
 
 int reader_init(){
 	//initialize poll timer
-	size_t poll_timeout = 1000;
+	size_t poll_timeout = DEFAULT_POLL_TIMEOUT;
 	struct itimerspec timer_cfg = {
 		0
 	};
@@ -75,6 +87,67 @@ int reader_init(){
 	return reader_init_backend();
 }
 
+static void reader_expire(){
+	size_t n = 0;
+	for(n = 0; n < MAX_TAGS; n++){
+		tags[n].flags &= ~(FLAG_ACTIVE);
+	}
+}
+
+static int reader_process(){
+	size_t n = 0;
+	for(n = 0; n < MAX_TAGS; n++){
+		if(tags[n].flags & FLAG_ACTIVE){
+			if(!(tags[n].flags & FLAG_CORE_NOTIFIED)){
+				//new tag
+				//TODO
+				printf("Tag index %lu detected\n", n);
+				tags[n].flags |= FLAG_CORE_NOTIFIED;
+			}
+		}
+		else{
+			if(tags[n].flags & FLAG_CORE_NOTIFIED){
+				//tag was removed
+				//TODO
+				printf("Tag index %lu removed\n", n);
+			}
+
+			//reset all flags
+			tags[n].flags = 0;
+		}
+	}
+	return 0;
+}
+
+int reader_tag_present(nfc_tag_info_t tag){
+	size_t n = 0;
+
+	//check if tag already known
+	for(n = 0; n < MAX_TAGS; n++){
+		if((tags[n].flags & (FLAG_ACTIVE | FLAG_CORE_NOTIFIED))
+				&& tags[n].info.uid_length == tag.uid_length
+				&& !memcmp(tags[n].info.uid, tag.uid, tag.uid_length)){
+			//mark still active
+			tags[n].flags |= FLAG_ACTIVE;
+			return 0;
+		}
+	}
+
+	//if not, add it
+	for(n = 0; n < MAX_TAGS; n++){
+		if(!tags[n].flags){
+			tags[n].flags |= FLAG_ACTIVE;
+			memcpy(&(tags[n].info), &tag, sizeof(tag));
+			return 0;
+		}
+	}
+
+	//realistically, this will never happen as most readers barely
+	//provide enough energy to power two tags in the field
+	printf("Maximum of active tags reached, ignored\n");
+	return 0;
+}
+
 int reader_handle(int fd){
 	uint8_t buffer[1024];
 
@@ -83,7 +156,7 @@ int reader_handle(int fd){
 		read(fd, buffer, sizeof(buffer));
 
 		//mark all tags expired
-		//TODO
+		reader_expire();
 
 		//scan all tags
 		if(reader_backend_scan()){
@@ -91,7 +164,7 @@ int reader_handle(int fd){
 		}
 
 		//handle changes in active set
-		//TODO
+		return reader_process();
 	}
 
 	if(reader_backend_handle){
diff --git a/reader_yhy.c b/reader_yhy.c
index 7ece702..9cb386f 100644
--- a/reader_yhy.c
+++ b/reader_yhy.c
@@ -42,7 +42,26 @@ int handle(int fd){
 }
 
 int scan(){
-	printf("Scanning field\n");
+	nfc_tag_info_t card = {
+		0
+	};
+
+	uint16_t atqa = 0;
+	uint8_t sak = 0;
+
+	if(!yhy_sync_request(reader_fd, 1, &atqa)){
+		return 0;
+	}
+
+	card.uid_length = yhy_sync_anticoll(reader_fd, card.uid, sizeof(card.uid));
+	if(!card.uid_length){
+		return 0;
+	}
+
+	yhy_sync_select(reader_fd, card.uid, card.uid_length, &sak);
+	yhy_sync_hlta(reader_fd);
+
+	reader_tag_present(card);
 	return 0;
 }
 
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