sr: fx2lafw: Avoid unnecessary alloc/free combo

[libsigrok.git] / hardware / fx2lafw / fx2lafw.c

diff --git a/hardware/fx2lafw/fx2lafw.c b/hardware/fx2lafw/fx2lafw.c
index d38a199923ed6f141f680798cd1369b18b513afc..c03c6b87391726d59d024743d11fe5803da91d9e 100644 (file)
--- a/hardware/fx2lafw/fx2lafw.c
+++ b/hardware/fx2lafw/fx2lafw.c
@@ -696,6 +696,30 @@ static void free_transfer(struct libusb_transfer *transfer)
 
 }
 
+static void resubmit_transfer(struct libusb_transfer *transfer)
+{
+       uint8_t *new_buf;
+
+       /* Increase buffer size to 4096 */
+       if (transfer->length != 4096) {
+               new_buf = g_try_malloc(4096);
+               /* If allocation of the new buffer fails, just vdo not bother and
+                * continue to use the old one. */
+               if (new_buf) {
+                       g_free(transfer->buffer);
+                       transfer->buffer = new_buf;
+                       transfer->length = 4096;
+               }
+       }
+
+       if (libusb_submit_transfer(transfer) != 0) {
+               free_transfer(transfer);
+               /* TODO: Stop session? */
+               /* TODO: Better error message. */
+               sr_err("fx2lafw: %s: libusb_submit_transfer error.", __func__);
+       }
+}
+
 static void receive_transfer(struct libusb_transfer *transfer)
 {
        /* TODO: These statics have to move to the ctx struct. */
@@ -704,7 +728,6 @@ static void receive_transfer(struct libusb_transfer *transfer)
        struct sr_datafeed_logic logic;
        struct context *ctx = transfer->user_data;
        int trigger_offset, i;
-       uint8_t *new_buf;
 
        /*
         * If acquisition has already ended, just free any queued up
@@ -723,21 +746,6 @@ static void receive_transfer(struct libusb_transfer *transfer)
        const int sample_width = ctx->sample_wide ? 2 : 1;
        const int cur_sample_count = transfer->actual_length / sample_width;
 
-       /* Fire off a new request. */
-       if (!(new_buf = g_try_malloc(4096))) {
-               sr_err("fx2lafw: %s: new_buf malloc failed.", __func__);
-               free_transfer(transfer);
-               return; /* TODO: SR_ERR_MALLOC */
-       }
-
-       transfer->buffer = new_buf;
-       transfer->length = 4096;
-       if (libusb_submit_transfer(transfer) != 0) {
-               /* TODO: Stop session? */
-               /* TODO: Better error message. */
-               sr_err("fx2lafw: %s: libusb_submit_transfer error.", __func__);
-       }
-
        if (transfer->actual_length == 0) {
                empty_transfer_count++;
                if (empty_transfer_count > MAX_EMPTY_TRANSFERS) {
@@ -746,8 +754,10 @@ static void receive_transfer(struct libusb_transfer *transfer)
                         * will work out that the samplecount is short.
                         */
                        abort_acquisition(ctx);
+                       free_transfer(transfer);
+               } else {
+                       resubmit_transfer(transfer);
                }
-               g_free(cur_buf);
                return;
        } else {
                empty_transfer_count = 0;
@@ -832,7 +842,8 @@ static void receive_transfer(struct libusb_transfer *transfer)
                 * ratio-sized buffer.
                 */
        }
-       g_free(cur_buf);
+
+       resubmit_transfer(transfer);
 }
 
 static int hw_dev_acquisition_start(int dev_index, void *cb_data)