Cut superfluous code down to the bone

avr/main.c

@@ -16,28 +16,11 @@ static volatile tabby_printer_packet_header header = {
     .size        = 0
 };
 
-static volatile uint8_t body[648];
-
 static volatile uint16_t sum = 0;
 
 static volatile uint16_t i = 0,
                          b = 0;
 
-static inline uint16_t checksum() {
-    uint16_t ret = header.data[2]
-                 + header.data[3]
-                 + header.data[4]
-                 + header.data[5];
-
-    size_t i;
-
-    for (i=0; i<header.size; i++) {
-        ret += ((uint8_t *)body)[i];
-    }
-
-    return ret;
-}
-
 /*
  * SPI byte receipt interrupt vector
  */
@@ -107,18 +90,14 @@ ISR(SPI_STC_vect) {
 
         default: {
             if (b < header.size) {
-                body[b++] = value;
+                b++;
-            } else if (b == header.size) {
-                sum >>= 8;
-                sum  |= value << 8;
 
+                SPDR = 0;
+            } else if (b == header.size) {
                 b++;
 
                 SPDR = 0;
             } else if (b == header.size + 1) {
-                sum >>= 8;
-                sum  |= value << 8;
-
                 b++;
 
                 SPDR = 0x81;

bin/main.c

@@ -44,8 +44,6 @@ int main(int argc, char **argv) {
     }
 
     while (1) {
-        uint8_t value;
-
         status = tabby_printer_packet_recv(fd, &header, &body, &checksum);
 
         if (status < 0) {
@@ -64,9 +62,6 @@ int main(int argc, char **argv) {
 
     return 0;
 
-error_link_send:
-    tabby_link_close(fd);
-
 error_link_open:
     return 1;
 }

include/tabby/link.h

@@ -17,12 +17,4 @@ int tabby_link_open(const char *dev);
 
 int tabby_link_close(int fd);
 
-ssize_t tabby_link_send(int fd, void *buf, uint16_t len);
-
-ssize_t tabby_link_recv(int fd, void *buf, uint16_t len);
-
-int tabby_link_set_clock_source(int fd, tabby_clock_source source);
-
-int tabby_link_set_clock_speed(int fd, tabby_clock_speed speed);
-
 #endif /* _TABBY_LINK_H */

src/link.c

@@ -11,7 +11,7 @@ int tabby_link_open(const char *dev) {
         goto error_open;
     }
 
-    attr.c_cflag = CS8 | CREAD;
+    attr.c_cflag   = CS8 | CREAD;
     attr.c_ispeed = TABBY_LINK_BAUD;
     attr.c_ospeed = TABBY_LINK_BAUD;
     attr.c_iflag  = IGNPAR;
@@ -37,38 +37,3 @@ error_open:
 int tabby_link_close(int fd) {
     return close(fd);
 }
-
-ssize_t tabby_link_send(int fd, void *buf, uint16_t len) {
-    uint8_t header[3] = {
-        TABBY_COMMAND_SEND, (len & 0xff00) >> 8, len & 0xff
-    };
-
-    if (write(fd, &header, sizeof(header)) < 0) {
-        goto error_write_header;
-    }
-
-    return write(fd, buf, (size_t)len);
-
-error_write_header:
-    return -1;
-}
-
-ssize_t tabby_link_recv(int fd, void *buf, uint16_t len) {
-    return read(fd, buf, (size_t)len);
-}
-
-int tabby_link_set_clock_source(int fd, tabby_clock_source source) {
-    uint8_t packet[2] = {
-        TABBY_COMMAND_CLOCK_SOURCE, source
-    };
-
-    return write(fd, &packet, sizeof(packet));
-}
-
-int tabby_link_set_clock_speed(int fd, tabby_clock_speed speed) {
-    uint8_t packet[2] = {
-        TABBY_COMMAND_CLOCK_SPEED, speed
-    };
-
-    return write(fd, &packet, sizeof(packet));
-}

src/printer.c

@@ -34,7 +34,7 @@ int tabby_printer_packet_recv(int fd, tabby_printer_packet_header *header,
 
     *sum = 0;
 
-    while ((len = tabby_link_recv(fd, &value, 1)) >= 0) {
+    while ((len = read(fd, &value, 1)) >= 0) {
         if (i == 0) {
             if (value == 0x88) {
                 header->preamble[0] = value;
@@ -91,5 +91,5 @@ int tabby_printer_response_send(int fd, uint8_t device, uint8_t status) {
         device, status
     };
 
-    return tabby_link_send(fd, &response, sizeof(response));
+    return write(fd, &response, sizeof(response));
 }