From 731236cf2099d1081a4fc9cd6be7ed93631b4ab1 Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Sun, 30 Sep 2018 10:37:48 -0400
Subject: [PATCH] usb_cdc: Add support for usb_send_ep0_progmem()

Add support for explicitly sending to the ep0 pipe from constant
"progmem" memory on the AVR.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 src/avr/pgm.h         | 2 ++
 src/generic/pgm.h     | 1 +
 src/generic/usb_cdc.c | 7 +++++--
 src/generic/usb_cdc.h | 1 +
 4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/avr/pgm.h b/src/avr/pgm.h
index ba68d8f9..031ba079 100644
--- a/src/avr/pgm.h
+++ b/src/avr/pgm.h
@@ -5,6 +5,8 @@
 
 #include <avr/pgmspace.h>
 
+#define NEED_PROGMEM 1
+
 #define READP(VAR) ({                                                   \
     _Pragma("GCC diagnostic push");                                     \
     _Pragma("GCC diagnostic ignored \"-Wint-to-pointer-cast\"");        \
diff --git a/src/generic/pgm.h b/src/generic/pgm.h
index bbdc0ba3..80ef4d1d 100644
--- a/src/generic/pgm.h
+++ b/src/generic/pgm.h
@@ -3,6 +3,7 @@
 // This header provides wrappers for the AVR specific "PROGMEM"
 // declarations on non-avr platforms.
 
+#define NEED_PROGMEM 0
 #define PROGMEM
 #define PSTR(S) S
 #define READP(VAR) VAR
diff --git a/src/generic/usb_cdc.c b/src/generic/usb_cdc.c
index 1e12f6a7..3899d7c3 100644
--- a/src/generic/usb_cdc.c
+++ b/src/generic/usb_cdc.c
@@ -290,7 +290,7 @@ static const struct descriptor_s {
 
 // State tracking
 enum {
-    UX_READ = 1<<0, UX_SEND = 1<<1, UX_SEND_ZLP = 1<<2
+    UX_READ = 1<<0, UX_SEND = 1<<1, UX_SEND_PROGMEM = 1<<2, UX_SEND_ZLP = 1<<3
 };
 
 static void *usb_xfer_data;
@@ -315,6 +315,8 @@ usb_do_xfer(void *data, uint_fast8_t size, uint_fast8_t flags)
         int_fast8_t ret;
         if (flags & UX_READ)
             ret = usb_read_ep0(data, xs);
+        else if (NEED_PROGMEM && flags & UX_SEND_PROGMEM)
+            ret = usb_send_ep0_progmem(data, xs);
         else
             ret = usb_send_ep0(data, xs);
         if (ret == xs) {
@@ -359,7 +361,8 @@ usb_req_get_descriptor(struct usb_ctrlrequest *req)
         const struct descriptor_s *d = &cdc_descriptors[i];
         if (READP(d->wValue) == req->wValue
             && READP(d->wIndex) == req->wIndex) {
-            uint_fast8_t size = READP(d->size), flags = UX_SEND;
+            uint_fast8_t size = READP(d->size);
+            uint_fast8_t flags = NEED_PROGMEM ? UX_SEND_PROGMEM : UX_SEND;
             if (size > req->wLength)
                 size = req->wLength;
             else if (size < req->wLength)
diff --git a/src/generic/usb_cdc.h b/src/generic/usb_cdc.h
index e152916d..21646900 100644
--- a/src/generic/usb_cdc.h
+++ b/src/generic/usb_cdc.h
@@ -16,6 +16,7 @@ int_fast8_t usb_read_bulk_out(void *data, uint_fast8_t max_len);
 int_fast8_t usb_send_bulk_in(void *data, uint_fast8_t len);
 int_fast8_t usb_read_ep0(void *data, uint_fast8_t max_len);
 int_fast8_t usb_send_ep0(const void *data, uint_fast8_t len);
+int_fast8_t usb_send_ep0_progmem(const void *data, uint_fast8_t len);
 void usb_stall_ep0(void);
 void usb_set_address(uint_fast8_t addr);
 void usb_set_configure(void);