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authorAsbjørn Sloth Tønnesen <ast@2e8.dk>2023-07-09 00:18:48 +0000
committerAsbjørn Sloth Tønnesen <ast@2e8.dk>2023-07-10 21:20:13 +0000
commit514d3e3b064def29f25a2a5f7c5447efcab3ccf8 (patch)
treed64a8978f9f692d90ecdbf5bc156ae00c3098be5
parentcec6695ba5615076f326ce0cd4e5f21fe6341db1 (diff)
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ql: optimize USB data flowfixes
Write column data into a buffer, and only write to USB once the buffer is filled past threshould. This reduces the amount of data frames on the USB bus, in a 429x336 sample image it was reduced from 1000 frames to about 100 frames, where the image data is only 20 frames, while the rest is mainly polling for status reponses.
-rw-r--r--src/ql.c32
1 files changed, 29 insertions, 3 deletions
diff --git a/src/ql.c b/src/ql.c
index 1023dbe..31bd24b 100644
--- a/src/ql.c
+++ b/src/ql.c
@@ -13,21 +13,29 @@
#include <string.h>
#include <time.h>
+#define QL_XMIT_SIZE 4096
+#define QL_BUF_SIZE (QL_XMIT_SIZE * 2)
+
struct ql_ctx {
char *printer;
int fd;
+ ssize_t pos;
+ char buf[QL_BUF_SIZE];
};
#define ESC 0x1b
#define STATUS_READ_TIMEOUT 5 /* seconds */
-#define full_write(ctx, buf) (retry_write(ctx, buf, sizeof(buf)) == (ssize_t)sizeof(buf))
+#define partial_write(ctx, buf) (do_write(ctx, buf, sizeof(buf), 0) == (ssize_t)sizeof(buf))
+#define full_write(ctx, buf) (do_write(ctx, buf, sizeof(buf), 1) == (ssize_t)sizeof(buf))
-ssize_t retry_write(ql_ctx_t ctx, const char *buf, size_t len)
+ssize_t retry_write(ql_ctx_t ctx)
{
int fd = ctx->fd;
size_t written = 0;
+ size_t len = ctx->pos;
+ char *buf = (char *)&ctx->buf;
int retval;
fd_set wfds;
@@ -54,9 +62,27 @@ ssize_t retry_write(ql_ctx_t ctx, const char *buf, size_t len)
written += n;
}
}
+ if (written == len) {
+ ctx->pos = 0;
+ }
return written;
}
+static ssize_t do_write(ql_ctx_t ctx, const char *buf, ssize_t len, int flush_buffer)
+{
+ if (ctx->pos + len >= QL_BUF_SIZE)
+ return 0;
+
+ memcpy(ctx->buf + ctx->pos, buf, len);
+ ctx->pos += len;
+
+ ssize_t pos = ctx->pos;
+ if (flush_buffer || pos > QL_XMIT_SIZE) {
+ return retry_write(ctx) == pos ? len : 0;
+ }
+ return len;
+}
+
static void get_mono_time(struct timespec *tp)
{
if (clock_gettime(CLOCK_MONOTONIC, tp) == -1) {
@@ -240,7 +266,7 @@ bool ql_print_raster_image(ql_ctx_t ctx, const ql_status_t * status,
block[1] = 0;
block[2] = dn;
pack_column((uint8_t *) block + 3, dn, w, img, cfg->threshold);
- if (!full_write(ctx, block))
+ if (!partial_write(ctx, block))
return false;
}