ols: Fix RLE count handling

[libsigrok.git] / hardware / openbench-logic-sniffer / protocol.c

diff --git a/hardware/openbench-logic-sniffer/protocol.c b/hardware/openbench-logic-sniffer/protocol.c
index c8b416857e73aae52b57309bd496cc9ec3112184..6082fb3e41adcdcf29429a2f2b905f62e060b5fd 100644 (file)
--- a/hardware/openbench-logic-sniffer/protocol.c
+++ b/hardware/openbench-logic-sniffer/protocol.c
@@ -340,7 +340,8 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
        struct sr_dev_inst *sdi;
        GSList *l;
        uint32_t sample;
-       int num_channels, offset, i, j;
+       int num_channels, offset, j;
+       unsigned int i;
        unsigned char byte;
 
        drvc = di->priv;
@@ -394,23 +395,22 @@ SR_PRIV int ols_receive_data(int fd, int revents, void *cb_data)
                devc->sample[devc->num_bytes++] = byte;
                sr_dbg("Received byte 0x%.2x.", byte);
                if (devc->num_bytes == num_channels) {
-                       /* Got a full sample. */
+                       /* Got a full sample. Convert from the OLS's little-endian
+                        * sample to the local format. */
                        sample = devc->sample[0] | (devc->sample[1] << 8) \
                                        | (devc->sample[2] << 16) | (devc->sample[3] << 24);
                        sr_dbg("Received sample 0x%.*x.", devc->num_bytes * 2, sample);
                        if (devc->flag_reg & FLAG_RLE) {
                                /*
-                                * In RLE mode -1 should never come in as a
-                                * sample, because bit 31 is the "count" flag.
+                                * In RLE mode the high bit of the sample is the
+                                * "count" flag, meaning this sample is the number
+                                * of times the previous sample occurred.
                                 */
                                if (devc->sample[devc->num_bytes - 1] & 0x80) {
-                                       devc->sample[devc->num_bytes - 1] &= 0x7f;
-                                       /*
-                                        * FIXME: This will only work on
-                                        * little-endian systems.
-                                        */
+                                       /* Clear the high bit. */
+                                       sample &= ~(0x80 << (devc->num_bytes - 1) * 8);
                                        devc->rle_count = sample;
-                                       sr_dbg("RLE count: %d.", devc->rle_count);
+                                       sr_dbg("RLE count: %u.", devc->rle_count);
                                        devc->num_bytes = 0;
                                        return TRUE;
                                }