From 105cebb38935b4052ac71694b16c60f8f8ac7813 Mon Sep 17 00:00:00 2001
From: Joerg Wunsch <j@uriah.heep.sax.de>
Date: Wed, 24 Nov 2021 22:06:31 +0000
Subject: [PATCH] patch #9327: ft245r.c: add TPI support (patches 1-4)
Submitted by David Mosberger-Tang:
Optimize TPI programming speed by reducing number of USB reads.
Specifically, when writing to the FTDI chip (without needing the data
it accumulates), simply increment a count of how many bytes the next
read should ignore. Thus, if there is one or more write followed by a
read, we only need to read from the device once.
Improves TPI programming speed by another factor of 2.
git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@1485 81a1dc3b-b13d-400b-aceb-764788c761c2
---
ChangeLog | 7 +++++++
ft245r.c | 21 ++++++++++++++++-----
2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 92032451..c9d215f3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2021-11-24 Joerg Wunsch <j.gnu@uriah.heep.sax.de>
+
+ Submitted by David Mosberger-Tang:
+ patch #9327: ft245r.c: add TPI support (patches 1-4)
+ * ft245r.c (ft245r_recv): Optimize TPI programming
+ speed by reducing number of USB reads.
+
2021-11-24 Joerg Wunsch <j.gnu@uriah.heep.sax.de>
Submitted by David Mosberger-Tang:
diff --git a/ft245r.c b/ft245r.c
index 588b099d..c2bfb561 100644
--- a/ft245r.c
+++ b/ft245r.c
@@ -161,6 +161,9 @@ static pthread_t readerthread;
static sem_t buf_data, buf_space;
static unsigned char buffer[BUFSIZE];
static int head, tail;
+static struct {
+ int discard; // # of bytes to discard during read
+} rx;
static void add_to_buf (unsigned char c) {
int nh;
@@ -206,15 +209,24 @@ static int ft245r_send(PROGRAMMER * pgm, unsigned char * buf, size_t len) {
return 0;
}
+static int ft245r_send_and_discard(PROGRAMMER * pgm, unsigned char * buf,
+ size_t len) {
+ rx.discard += len;
+ return ft245r_send(pgm, buf, len);
+}
+
static int ft245r_recv(PROGRAMMER * pgm, unsigned char * buf, size_t len) {
- int i;
+ int i = 0;
// Copy over data from the circular buffer..
// XXX This should timeout, and return error if there isn't enough
// data.
- for (i=0; i<len; i++) {
+ while (i < len) {
sem_wait (&buf_data);
- buf[i] = buffer[tail];
+ if (rx.discard > 0)
+ --rx.discard;
+ else
+ buf[i++] = buffer[tail];
if (tail == (BUFSIZE -1)) tail = 0;
else tail++;
sem_post (&buf_space);
@@ -645,8 +657,7 @@ static int ft245r_tpi_tx(PROGRAMMER * pgm, uint8_t byte) {
int len;
len = set_tpi_data(pgm, buf, byte);
- ft245r_send(pgm, buf, len);
- ft245r_recv(pgm, buf, len);
+ ft245r_send_and_discard(pgm, buf, len);
return 0;
}