From d4402aa29606866476f982c6667f3deba94b9593 Mon Sep 17 00:00:00 2001
From: Jef Driesen <jef@libdivecomputer.org>
Date: Thu, 22 Jun 2023 20:42:12 +0200
Subject: [PATCH] Add support for the WDBI function

The RDBI (Read Data by Identifier) has a WDBI (Write Data by Identifier)
counterpart, which supports changing settings on the dive computer.
---
 src/shearwater_common.c | 37 +++++++++++++++++++++++++++++++++++++
 src/shearwater_common.h |  3 +++
 2 files changed, 40 insertions(+)

diff --git a/src/shearwater_common.c b/src/shearwater_common.c
index c184bb3..7a47f58 100644
--- a/src/shearwater_common.c
+++ b/src/shearwater_common.c
@@ -39,6 +39,9 @@
 #define RDBI_REQUEST  0x22
 #define RDBI_RESPONSE 0x62
 
+#define WDBI_REQUEST  0x2E
+#define WDBI_RESPONSE 0x6E
+
 dc_status_t
 shearwater_common_setup (shearwater_common_device_t *device, dc_context_t *context, dc_iostream_t *iostream)
 {
@@ -552,6 +555,40 @@ shearwater_common_rdbi (shearwater_common_device_t *device, unsigned int id, uns
 	return status;
 }
 
+dc_status_t
+shearwater_common_wdbi (shearwater_common_device_t *device, unsigned int id, const unsigned char data[], unsigned int size)
+{
+	dc_status_t status = DC_STATUS_SUCCESS;
+	dc_device_t *abstract = (dc_device_t *) device;
+
+	if (size + 3 > SZ_PACKET) {
+		return DC_STATUS_INVALIDARGS;
+	}
+
+	// Transfer the request.
+	unsigned int n = 0;
+	unsigned char request[SZ_PACKET] = {
+		WDBI_REQUEST,
+		(id >> 8) & 0xFF,
+		(id     ) & 0xFF};
+	if (size) {
+		memcpy (request + 3, data, size);
+	}
+	unsigned char response[SZ_PACKET];
+	status = shearwater_common_transfer (device, request, size + 3, response, sizeof (response), &n);
+	if (status != DC_STATUS_SUCCESS) {
+		return status;
+	}
+
+	// Verify the response.
+	if (n < 3 || response[0] != WDBI_RESPONSE || response[1] != request[1] || response[2] != request[2]) {
+		ERROR (abstract->context, "Unexpected response packet.");
+		return DC_STATUS_PROTOCOL;
+	}
+
+	return status;
+}
+
 unsigned int
 shearwater_common_get_model (shearwater_common_device_t *device, unsigned int hardware)
 {
diff --git a/src/shearwater_common.h b/src/shearwater_common.h
index 8f8e356..1c25b75 100644
--- a/src/shearwater_common.h
+++ b/src/shearwater_common.h
@@ -67,6 +67,9 @@ shearwater_common_download (shearwater_common_device_t *device, dc_buffer_t *buf
 dc_status_t
 shearwater_common_rdbi (shearwater_common_device_t *device, unsigned int id, unsigned char data[], unsigned int size);
 
+dc_status_t
+shearwater_common_wdbi (shearwater_common_device_t *device, unsigned int id, const unsigned char data[], unsigned int size);
+
 unsigned int
 shearwater_common_get_model (shearwater_common_device_t *device, unsigned int hardware);