You know I never actually compiled any of this yet

avr/main.c

@@ -22,6 +22,9 @@ static volatile tabby_avr_buffer buffer = {
     .cur = 0
 };
 
+static tabby_clock_source source = TABBY_CLOCK_SOURCE_INTERNAL;
+static tabby_clock_speed  speed  = TABBY_CLOCK_SPEED_8192HZ;
+
 /*
  * Internal clock source interrupt vector
  */
@@ -44,10 +47,11 @@ ISR(TIM0_COMPB_vect) {
         uart_putchar(value_in, NULL);
 
         if (buffer.cur < buffer.len) {
-            value_out = buffer.data[++buffer.cur];
+            value_out = buffer.data[buffer.cur++];
         } else {
             buffer.len = 0;
             buffer.cur = 0;
+            buffer.read = 0;
         }
 
         bits = 8;
@@ -67,10 +71,11 @@ ISR(SPI_STC_vect) {
     uart_putchar(SPDR);
 
     if (buffer.cur < buffer.len) {
-        SPDR = buffer.data[++buffer.cur];
+        SPDR = buffer.data[buffer.cur++];
     } else {
         buffer.len  = 0;
         buffer.cur  = 0;
+        buffer.read = 0;
     }
 }
 
@@ -185,46 +190,78 @@ int main() {
         received++;
 
         switch (state) {
-            case TABBY_COMMAND_NONE: {
+            case TABBY_COMMAND_NONE:
-                if (last == 0 && c == TABBY_PACKET_START) {
-                    continue;
-                } else if (last == TABBY_PACKET_START) {
                 state = c;
-                }
 
                 break;
-            }
 
-            case TABBY_COMMAND_SEND: {
+            case TABBY_COMMAND_SEND:
-                if (received == 3 || received == 4) {
+                if (received == 2 || received == 3) {
                     buffer.len = (buffer.len >> 8) | (c << 8);
                 } else {
-                    buffer.data[buffer.cur++] = c;
+                    buffer.data[buffer.read++] = c;
+
+                    if (buffer.read == buffer.len) {
+                        goto reset;
+                    }
                 }
 
                 break;
-            }
 
             case TABBY_COMMAND_CLOCK_SOURCE:
-            case TABBY_COMMAND_CLOCK_SPEED:
+                switch (c) {
+                    case TABBY_CLOCK_SOURCE_INTERNAL:
+                        source = c;
+
+                        setup_clock_internal(speed);
+
+                        goto reset;
+
+                    case TABBY_CLOCK_SOURCE_EXTERNAL:
+                        source = c;
+
+                        setup_clock_external();
+
+                        goto reset;
 
                     default:
-                goto error_invalid_packet;
+                        goto reset;
+                }
+
+            case TABBY_COMMAND_CLOCK_SPEED:
+                switch (c) {
+                    case TABBY_CLOCK_SPEED_8192HZ:
+                    case TABBY_CLOCK_SPEED_16384HZ:
+                    case TABBY_CLOCK_SPEED_262144HZ:
+                    case TABBY_CLOCK_SPEED_524288HZ:
+                        speed = c;
+
+                        if (source == TABBY_CLOCK_SOURCE_INTERNAL) {
+                            setup_clock_internal(speed);
+                        }
+
+                        goto reset;
+
+                    default:
+                        goto reset;
+                }
+
+            default:
+                goto reset;
         }
 
         last = c;
 
-        received++;
-
         continue;
 
-error_invalid_packet:
+reset:
         state    = TABBY_COMMAND_NONE;
         last     = 0;
         received = 0;
 
-        buffer.cur = 0;
         buffer.len  = 0;
+        buffer.cur  = 0;
+        buffer.read = 0;
     }
 
     return 0;

include/tabby.h

@@ -3,6 +3,5 @@
 
 #include <tabby/clock.h>
 #include <tabby/command.h>
-#include <tabby/packet.h>
 
 #endif /* _TABBY_H */

include/tabby/avr/buffer.h

@@ -3,19 +3,14 @@
 
 #include <sys/types.h>
 
-#include <tabby/packet.h>
-
 #define TABBY_AVR_BUFFER_SIZE 1024
 
 typedef struct _tabby_avr_buffer {
     uint16_t len,
-             cur;
+             cur,
-
+             read;
-    union {
-        tabby_packet header;
 
     uint8_t data[TABBY_AVR_BUFFER_SIZE];
-    };
 } tabby_avr_buffer;
 
 #endif /* _TABBY_AVR_BUFFER_H */

include/tabby/packet.h

@@ -1,16 +0,0 @@
-#ifndef _TABBY_PACKET_H
-#define _TABBY_PACKET_H
-
-#define TABBY_PACKET_START   0xff
-#define TABBY_PACKET_MAX_LEN 1024
-
-#include <tabby/command.h>
-
-typedef struct _tabby_packet {
-    uint8_t start,
-            command;
-
-    uint16_t len;
-} tabby_packet;
-
-#endif /* _TABBY_PACKET_H */

src/link.c

@@ -40,9 +40,8 @@ int tabby_link_close(int fd) {
 }
 
 ssize_t tabby_link_send(int fd, char *buf, uint16_t len) {
-    tabby_packet header = {
+    uint8_t header[3] = {
-        .type  = htobe16(TABBY_COMMAND_SEND),
+        TABBY_COMMAND_SEND, len & 0xff00 >> 8, len & 0xff
-        .value = htobe16(len)
     };
 
     if (write(fd, &header, sizeof(header)) < 0) {
@@ -60,18 +59,16 @@ ssize_t tabby_link_recv(int fd, char *buf, uint16_t len) {
 }
 
 int tabby_link_set_clock_source(int fd, tabby_clock_source source) {
-    tabby_packet packet = {
+    uint8_t packet[2] = {
-        .command = htobe16(TABBY_COMMAND_CLOCK_SOURCE),
+        TABBY_COMMAND_CLOCK_SOURCE, source
-        .value   = htobe16(source)
     };
 
     return write(fd, &packet, sizeof(packet));
 }
 
 int tabby_link_set_clock_speed(int fd, tabby_clock_speed speed) {
-    tabby_packet packet = {
+    uint8_t packet[2] = {
-        .command = htobe16(TABBY_COMMAND_CLOCK_SPEED),
+        TABBY_COMMAND_CLOCK_SPEED, speed
-        .value   = htobe16(speed)
     };
 
     return write(fd, &packet, sizeof(packet));