Add MAIL_T macro; read framebuffer allocation response

1 files changed, 9 insertions, 3 deletions

diff --git a/src/mailbox.h b/src/mailbox.h
index b35c7a6..2104265 100644
--- a/src/mailbox.h
+++ b/src/mailbox.h
@@ -1,3 +1,9 @@
+/*
+References:
+  https://github-wiki-see.page/m/raspberrypi/firmware/wiki/Mailbox-property-interface
+  https://jsandler18.github.io/extra/prop-channel.html
+  https://jsandler18.github.io/extra/mailbox.html
+*/
 #pragma once
 
 #include <stdint.h>
@@ -6,6 +12,9 @@
 // must be aligned to a 16-byte boundary.
 #define MAIL_ALIGN 16
 
+// Type prefix for data arrays used as mail.
+#define MAIL_T volatile __attribute__((aligned(MAIL_ALIGN)))
+
 enum
 {
   PROPERTY_CHANNEL = 8,
@@ -55,9 +64,6 @@ typedef struct __attribute__((aligned(MAIL_ALIGN))) Mail {
   Tag      tags[];  // Variable quantity.
 } Mail;
 
-// TODO: Remove? Unused.
-#define MAIL_SIZE(TYPE) (sizeof(TYPE) + (2 * sizeof(uint32_t)))
-
 void        mbox_init();
 const Mail* mbox_read(uint8_t channel);
 void        mbox_write(uint8_t channel, volatile const void* mail);