get packet len to copy less data

src/libboard_artiq/src/drtioaux.rs

@@ -77,10 +77,9 @@ where F: FnOnce(&[u8]) -> Result<T, Error> {
             let read_ptr = (DRTIOAUX[linkidx].aux_read_pointer_read)() as usize;
             let ptr = (DRTIOAUX_MEM[linkidx].base + DRTIOAUX_MEM[linkidx].size / 2 + read_ptr * 0x400) as *mut u32;
             // work buffer to accomodate axi burst reads
-            // potentially: get length by checking the first byte to cut down on unnecessary copying
-            const LEN: usize = 1024;
-            let mut buf: [u8; LEN] = [0; LEN];
-            copy_work_buffer(ptr, buf.as_mut_ptr() as *mut u32, LEN as isize);
+            let len = Packet::get_aligned_size(*(ptr as *mut u8));
+            let mut buf: [u8; 1024] = [0; 1024];
+            copy_work_buffer(ptr, buf.as_mut_ptr() as *mut u32, len);
             let result = f(&buf);
             (DRTIOAUX[linkidx].aux_rx_present_write)(1);
             Ok(Some(result?))

src/libboard_artiq/src/drtioaux_async.rs

@@ -41,10 +41,9 @@ where F: FnOnce(&[u8]) -> Result<T, Error> {
             let read_ptr = (DRTIOAUX[linkidx].aux_read_pointer_read)() as usize;
             let ptr = (DRTIOAUX_MEM[linkidx].base + DRTIOAUX_MEM[linkidx].size / 2 + read_ptr * 0x400) as *mut u32;
             // work buffer to accomodate axi burst reads
-            // potentially: get length by checking the first byte to cut down on unnecessary copying
-            const LEN: usize = 1024;
-            let mut buf: [u8; LEN] = [0; LEN];
-            copy_work_buffer(ptr, buf.as_mut_ptr() as *mut u32, LEN as isize);
+            let len = Packet::get_aligned_size(*(ptr as *mut u8));
+            let mut buf: [u8; 1024] = [0; 1024];
+            copy_work_buffer(ptr, buf.as_mut_ptr() as *mut u32, len);
             let result = f(&buf);
             (DRTIOAUX[linkidx].aux_rx_present_write)(1);
             Ok(Some(result?))

src/libboard_artiq/src/drtioaux_proto.rs

@@ -1,9 +1,11 @@
 use core_io::{Error as IoError, Read, Write};
 use io::proto::{ProtoRead, ProtoWrite};
 
+const MAX_PACKET: usize = 1024;
+
 // maximum size of arbitrary payloads
 // used by satellite -> master analyzer, subkernel exceptions
-pub const SAT_PAYLOAD_MAX_SIZE: usize  = /*max size*/1024 - /*CRC*/4 - /*packet ID*/1 - /*last*/1 - /*length*/2;
+pub const SAT_PAYLOAD_MAX_SIZE: usize  = /*max size*/MAX_PACKET - /*CRC*/4 - /*packet ID*/1 - /*last*/1 - /*length*/2;
 // used by DDMA, subkernel program data (need to provide extra ID and destination)
 pub const MASTER_PAYLOAD_MAX_SIZE: usize = SAT_PAYLOAD_MAX_SIZE - /*source*/1 - /*destination*/1 - /*ID*/4;
 
@@ -962,4 +964,60 @@ impl Packet {
             _ => true,
         }
     }
+
+    pub fn get_aligned_size(first_byte: u8) -> isize {
+        // returns length of the packet given first byte, for work buffer
+        let unaligned_size = match first_byte {
+            0x00 => 1,  // Packet::EchoRequest
+            0x01 => 1,  // Packet::EchoReply
+            0x02 => 1,  // Packet::ResetRequest
+            0x03 => 1,  // Packet::ResetAck
+            0x04 => 1,  // Packet::TSCAck
+            0x20 => 2,  // Packet::DestinationStatusRequest
+            0x21 => 1,  // Packet::DestinationDownReply
+            0x22 => 1,  // Packet::DestinationOkReply
+            0x23 => 3,  // Packet::DestinationSequenceErrorReply
+            0x24 => 3,  // Packet::DestinationCollisionReply
+            0x25 => 3,  // Packet::DestinationBusyReply
+            0x30 => 34, // Packet::RoutingSetPath
+            0x31 => 2,  // Packet::RoutingSetRank
+            0x32 => 1,  // Packet::RoutingAck
+            0x40 => 5,  // Packet::MonitorRequest
+            0x41 => 9,  // Packet::MonitorReply
+            0x50 => 6,  // Packet::InjectionRequest
+            0x51 => 5,  // Packet::InjectionStatusRequest
+            0x52 => 2,  // Packet::InjectionStatusReply
+            0x80 => 3,  // Packet::I2cStartRequest
+            0x81 => 3,  // Packet::I2cRestartRequest
+            0x82 => 3,  // Packet::I2cStopRequest
+            0x83 => 4,  // Packet::I2cWriteRequest
+            0x84 => 3,  // Packet::I2cWriteReply
+            0x85 => 4,  // Packet::I2cReadRequest
+            0x86 => 3,  // Packet::I2cReadReply
+            0x87 => 2,  // Packet::I2cBasicReply
+            0x88 => 5,  // Packet::I2cSwitchSelectRequest
+            0x90 => 7,  // Packet::SpiSetConfigRequest
+            0x92 => 7,  // Packet::SpiWriteRequest
+            0x93 => 3,  // Packet::SpiReadRequest
+            0x94 => 6,  // Packet::SpiReadReply
+            0x95 => 2,  // Packet::SpiBasicReply
+            0xa0 => 2,  // Packet::AnalyzerHeaderRequest
+            0xa1 => 14, // Packet::AnalyzerHeader
+            0xa2 => 2,  // Packet::AnalyzerDataRequest
+            0xb1 => 8,  // Packet::DmaAddTraceReply
+            0xb2 => 7,  // Packet::DmaRemoveTraceRequest
+            0xb3 => 3,  // Packet::DmaRemoveTraceReply
+            0xb4 => 15, // Packet::DmaPlaybackRequest
+            0xb5 => 3,  // Packet::DmaPlaybackReply
+            0xb6 => 20, // Packet::DmaPlaybackStatus
+            0xc1 => 2,  // Packet::SubkernelAddDataReply
+            0xc4 => 8,  // Packet::SubkernelLoadRunRequest
+            0xc5 => 3,  // Packet::SubkernelLoadRunReply
+            0xc8 => 8,  // Packet::SubkernelFinished
+            0xc9 => 2,  // Packet::SubkernelExceptionRequest
+            0xcc => 2,  // Packet::SubkernelMessageAck
+            _ => MAX_PACKET-4
+        } + 4 /*CRC*/;
+        (unaligned_size + 7) as isize & -8 as isize
+    }
 }