increase programming speed by a factor of 4.

it now takes 5 seconds to program a xc3s400, which is the same time it
takes to program this chip with a parallel cable.

diff --git a/jtagkey.c b/jtagkey.c
index 9891f4b70302d77a43283db5dbbcf16de3c2454d..2be195451f13f2cbfa1aaa9c10ebd5666c420f8a 100644 (file)
--- a/jtagkey.c
+++ b/jtagkey.c
@@ -3,9 +3,10 @@
 #include "usb-driver.h"
 #include "jtagkey.h"
 
-#define USBBUFSIZE 384
+#define USBBUFSIZE 4096
 
 static struct ftdi_context ftdic;
+static unsigned int usb_maxlen = 0;
 
 int jtagkey_init(unsigned short vid, unsigned short pid) {
        int ret = 0;
@@ -31,12 +32,11 @@ int jtagkey_init(unsigned short vid, unsigned short pid) {
                return ret;
        }
 
-#if 0
-       if ((ret = ftdi_write_data_set_chunksize(&ftdic, 1))  != 0) {
-               fprintf(stderr, "unable to set write chunksize: %d (%s)\n", ret, ftdi_get_error_string(&ftdic));
+
+       if ((ret = ftdi_write_data_get_chunksize(&ftdic, &usb_maxlen))  != 0) {
+               fprintf(stderr, "unable to get write chunksize: %d (%s)\n", ret, ftdi_get_error_string(&ftdic));
                return ret;
        }
-#endif
 
        if ((ret = ftdi_set_latency_timer(&ftdic, 1))  != 0) {
                fprintf(stderr, "unable to set latency timer: %d (%s)\n", ret, ftdi_get_error_string(&ftdic));
@@ -51,7 +51,7 @@ int jtagkey_init(unsigned short vid, unsigned short pid) {
        c = 0x00;
        ftdi_write_data(&ftdic, &c, 1);
 
-       if ((ret = ftdi_set_bitmode(&ftdic, JTAGKEY_TCK|JTAGKEY_TDI|JTAGKEY_TMS|JTAGKEY_OEn, BITMODE_SYNCBB))  != 0) {
+       if ((ret = ftdi_set_bitmode(&ftdic, JTAGKEY_TCK|JTAGKEY_TDI|JTAGKEY_TMS|JTAGKEY_OEn, BITMODE_BITBANG))  != 0) {
                fprintf(stderr, "unable to enable bitbang mode: %d (%s)\n", ret, ftdi_get_error_string(&ftdic));
                return ret;
        }
@@ -110,14 +110,21 @@ int jtagkey_transfer(WD_TRANSFER *tr, int fd, unsigned int request, int ppbase,
 
        /* Write combining */
        if ((writepos-writebuf > sizeof(writebuf)-num) || (nread && writepos-writebuf)) {
+               unsigned char *pos = writebuf;
+               int len;
                DPRINTF("writing %d bytes due to %d following reads in %d chunks or full buffer\n", writepos-writebuf, nread, num);
 
-               ftdi_write_data(&ftdic, writebuf, writepos-writebuf);
+               len = writepos-pos;
+
+               while (pos < writepos) {
+                       if (len > usb_maxlen)
+                               len = usb_maxlen;
 
-               i = 0;
-               while (i < writepos-writebuf) {
-                       i += ftdi_read_data(&ftdic, readbuf, sizeof(readbuf));
+                       DPRINTF("combined write of %d/%d\n",len,writepos-pos);
+                       ftdi_write_data(&ftdic, pos, len);
+                       pos += len;
                }
+
                DPRINTF("read %d/%d bytes\n", i, writepos-writebuf);
                writepos = writebuf;
        }
@@ -200,14 +207,10 @@ int jtagkey_transfer(WD_TRANSFER *tr, int fd, unsigned int request, int ppbase,
        if (nread)
        {
                DPRINTF("writing %d bytes\n", writepos-writebuf);
-               ftdi_write_data(&ftdic, writebuf, writepos-writebuf);
-               DPRINTF("reading %d bytes\n", writepos-writebuf);
-
-               i = 0;
-               while (i < writepos-writebuf) {
-                       i += ftdi_read_data(&ftdic, readbuf, sizeof(readbuf));
+               for (i=0; i<writepos-writebuf; i++) {
+                       ftdi_write_data(&ftdic, writebuf+i, 1);
+                       ftdi_read_pins(&ftdic, readbuf+i);
                }
-               DPRINTF("read %d bytes\n", i);
 
 #ifdef DEBUG
                DPRINTF("write: ");