From 3b7f816a23a56167c7ebd5253394d21884ceb5eb Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Thu, 24 Oct 2024 14:10:07 +0200
Subject: [PATCH] feat: implement simple control usb read, writes

---
 include/usb.h |   9 ++++
 src/usb.c     | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 src/usb.c

diff --git a/include/usb.h b/include/usb.h
index cbbf155..848c3e2 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -191,4 +191,13 @@ typedef struct {
   uint8_t *bString;
 } usb_unicode_string_descriptor_t;
 
+void usb_send_descriptor(usb_descriptor_t* descriptor, uint32_t *fifo_tx_target);
+/* void usb_send_ack(uint32_t* fifo_tx_target); */
+void usb_send_configuration_descriptor(usb_configuration_descriptor_t* descriptor, uint32_t *fifo_tx_target);
+void usb_send_interface_descriptor(usb_interface_descriptor_t* descriptor, uint32_t *fifo_tx_target);
+void usb_send_endpoint_descriptor(usb_endpoint_descriptor_t* descriptor, uint32_t *fifo_tx_target);
+void usb_send_string_descriptor_zero(usb_string_descriptor_zero_t* string_descriptor, uint32_t *fifo_tx_target);
+void usb_send_unicode_string_descriptor(usb_unicode_string_descriptor_t* string_descriptor, uint32_t *fifo_tx_target);
+
+
 #endif // USB_H
diff --git a/src/usb.c b/src/usb.c
new file mode 100644
index 0000000..a4be090
--- /dev/null
+++ b/src/usb.c
@@ -0,0 +1,115 @@
+#include "usb.h"
+
+typedef union {
+  uint32_t word;
+  uint16_t halfwords[2];
+  uint8_t bytes[4];
+} usb_data_t;
+
+void usb_generic_send(uint8_t* data, uint16_t size, uint32_t *fifo_tx_target) {
+  usb_data_t tx_data;
+  uint8_t subWordBytes = size % 4;
+  uint8_t wordCount = size / 4;
+
+  for (uint8_t i = 0; i < wordCount; i++) {
+    tx_data.word = *((uint32_t*)data);
+    *fifo_tx_target = tx_data.word;
+    data += 4;
+  }
+
+  // TODO: check where to put it... beginning, end...
+  if (subWordBytes != 0) {
+    tx_data.word = 0;
+    for (uint8_t i = 0; i < subWordBytes; i++) {
+      tx_data.bytes[i] = *(data + i);
+    }
+    *fifo_tx_target = tx_data.word;
+  }
+}
+
+void usb_generic_read(uint8_t *data, uint16_t size, uint32_t *fifo_rx_source) {
+  usb_data_t rx_data;
+  uint8_t subWordBytes = size % 4;
+  uint8_t wordCount = size / 4;
+
+  for (uint8_t i = 0; i < wordCount; i++) {
+    rx_data.word = *fifo_rx_source;
+    *((uint32_t*)data) = rx_data.word;
+    data += 4;
+  }
+
+  // TODO: check where to put it... beginning, end...
+  if (subWordBytes > 0) {
+    rx_data.word = 0;
+    for (uint8_t i = 0; i < subWordBytes; i++) {
+      *(data + i) = rx_data.bytes[i];
+    }
+  }
+}
+
+void usb_send_descriptor(usb_descriptor_t *descriptor,
+                         uint32_t *fifo_tx_target) {
+  usb_generic_send((uint8_t*)descriptor, descriptor->bLength, fifo_tx_target);
+}
+
+void usb_send_configuration_descriptor(
+    usb_configuration_descriptor_t *descriptor, uint32_t *fifo_tx_target) {
+  descriptor->header.bDescriptorType = DESCRIPTOR_CONFIGURATION;
+  descriptor->header.bLength = sizeof(usb_configuration_descriptor_t);
+  usb_send_descriptor(&descriptor->header, fifo_tx_target);
+}
+void usb_send_interface_descriptor(usb_interface_descriptor_t *descriptor,
+                                   uint32_t *fifo_tx_target) {
+  descriptor->header.bDescriptorType = DESCRIPTOR_INTERFACE;
+  descriptor->header.bLength = sizeof(usb_interface_descriptor_t);
+  usb_send_descriptor(&descriptor->header, fifo_tx_target);
+}
+void usb_send_endpoint_descriptor(usb_endpoint_descriptor_t *descriptor,
+                                  uint32_t *fifo_tx_target) {
+  descriptor->header.bDescriptorType = DESCRIPTOR_ENDPOINT;
+  descriptor->header.bLength = sizeof(usb_endpoint_descriptor_t);
+  usb_send_descriptor(&descriptor->header, fifo_tx_target);
+}
+
+void usb_send_string_descriptor_zero(usb_string_descriptor_zero_t *string_descriptor,
+                              uint32_t *fifo_tx_target) {
+  usb_data_t data;
+  data.word = 0;
+
+  data.bytes[0] = string_descriptor->header.bLength;
+  data.bytes[1] = string_descriptor->header.bDescriptorType;
+
+  if (string_descriptor->header.bLength == 2) {
+    *fifo_tx_target = data.word;
+    return;
+  }
+
+  data.halfwords[1] = string_descriptor->wLANGID[0];
+
+  *fifo_tx_target = data.word;
+
+  // TODO: Now the rest only from wLANGID[1..]
+  if (string_descriptor->header.bLength > 4) {
+    usb_generic_send((uint8_t *)&string_descriptor->wLANGID[1],
+                     string_descriptor->header.bLength - 4,
+                     fifo_tx_target);
+  }
+}
+void usb_send_unicode_string_descriptor(
+    usb_unicode_string_descriptor_t *string_descriptor,
+    uint32_t *fifo_tx_target) {
+
+  usb_data_t data = { .word = 0 };
+  data.halfwords[0] = *((uint16_t*)string_descriptor);
+  if (string_descriptor->bString != 0 && string_descriptor->header.bLength > 2) {
+    // NOTE: if the string had length of just one, there would be two bytes
+    // read here. That shouldn't usually matter much, so we don't care about
+    // that here.
+    data.halfwords[1] = *((uint16_t*)string_descriptor->bString);
+  }
+  *fifo_tx_target = data.word;
+
+  if (string_descriptor->header.bLength > 4) {
+    usb_generic_send(&string_descriptor->bString[2], string_descriptor->header.bLength - 4, fifo_tx_target);
+  }
+}
-- 
2.48.1