speed up jtag xfers

diff --git a/jtag_tap.c b/jtag_tap.c
index 5236243260ddddaec96e95678384bc63f762307e..fe60e18147b7afe70896a4e16422426b9eb1fd8e 100644 (file)
--- a/jtag_tap.c
+++ b/jtag_tap.c
@@ -175,30 +175,51 @@ void jtag_tap_shift(
        bool must_end)
 {
 
+       
+
+       printf("jtag_tap_shift(%u)\n", data_bits);
        uint32_t bit_count = data_bits;
        uint32_t byte_count = (data_bits + 7) / 8;
 
-       for (uint32_t i = 0; i < byte_count; ++i) {
-               uint8_t byte_out = input_data[i];
-               uint8_t tdo_byte = 0;
-               for (int j = 0; j < 8 && bit_count-- > 0; ++j) {
-            bool tms = false;
-            bool tdi = false;
-                       if (bit_count == 0 && must_end) {
-                tms = true;
-                               jtag_state_ack(1);
-                       }
-                       if (byte_out & 1) {
-                               tdi = true;
-                       } else {
-                               tdi = false;
-                       }
-                       byte_out >>= 1;
-                       bool tdo = jtag_pulse_clock_and_read_tdo(tms, tdi);
-                       tdo_byte |= tdo << j;
+       uint8_t byte_out = input_data[byte_count-1];
+       uint8_t tdo_byte = 0;
+
+
+       if(byte_count > 1){
+               mpsse_send_byte( MC_DATA_IN | MC_DATA_OUT | MC_DATA_LSB |MC_DATA_OCN);
+               mpsse_send_byte((byte_count - 2) & 0xFF);               
+               mpsse_send_byte((byte_count - 2) >> 8); 
+
+               for(int i = 0; i < byte_count-1; i++){                          
+               mpsse_send_byte(input_data[i]);
+               output_data[i] = mpsse_recv_byte();
+               bit_count -= 8;
                }
-               output_data[i] = tdo_byte;
+
        }
+
+       printf("loop2: %u \n", bit_count);
+       for (int j = 0; j < 8 && bit_count-- > 0; ++j) {
+               
+               bool tms = false;
+               bool tdi = false;
+               if (bit_count == 0 && must_end) {
+                       tms = true;
+                       jtag_state_ack(1);
+               }
+               if (byte_out & 1) {
+                       tdi = true;
+               } else {
+                       tdi = false;
+               }
+               byte_out >>= 1;
+               bool tdo = jtag_pulse_clock_and_read_tdo(tms, tdi);
+               tdo_byte |= tdo << j;
+       
+       }
+       output_data[byte_count-1] = tdo_byte;
+               
+       
 }
 
 void jtag_state_ack(bool tms)