X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fhardware%2Fasix-sigma%2Fprotocol.c;h=d2670b4c3a974e503330f9a1564fd2b1737772e1;hb=7b365c47198890da8541a6daf04697c7c7ac88d4;hp=b23b26ff832cca1cb4d0d8aa1d938c1631512bf2;hpb=4154a516de818ace3aabfe5e44cf4c81986074e7;p=libsigrok.git

diff --git a/src/hardware/asix-sigma/protocol.c b/src/hardware/asix-sigma/protocol.c
index b23b26ff..d2670b4c 100644
--- a/src/hardware/asix-sigma/protocol.c
+++ b/src/hardware/asix-sigma/protocol.c
@@ -105,9 +105,9 @@ SR_PRIV int sigma_write_register(uint8_t reg, uint8_t *data, size_t len,
 	uint8_t buf[80];
 	int idx = 0;
 
-	if ((len + 2) > sizeof(buf)) {
+	if ((2 * len + 2) > sizeof(buf)) {
 		sr_err("Attempted to write %zu bytes, but buffer is too small.",
-		       len + 2);
+		       len);
 		return SR_ERR_BUG;
 	}
 
@@ -530,6 +530,7 @@ SR_PRIV int sigma_set_samplerate(const struct sr_dev_inst *sdi, uint64_t sampler
 	drvc = sdi->driver->context;
 	ret = SR_OK;
 
+	/* Reject rates that are not in the list of supported rates. */
 	for (i = 0; i < samplerates_count; i++) {
 		if (samplerates[i] == samplerate)
 			break;
@@ -537,6 +538,11 @@ SR_PRIV int sigma_set_samplerate(const struct sr_dev_inst *sdi, uint64_t sampler
 	if (i >= samplerates_count || samplerates[i] == 0)
 		return SR_ERR_SAMPLERATE;
 
+	/*
+	 * Depending on the samplerates of 200/100/50- MHz, specific
+	 * firmware is required and higher rates might limit the set
+	 * of available channels.
+	 */
 	if (samplerate <= SR_MHZ(50)) {
 		ret = upload_firmware(drvc->sr_ctx, 0, devc);
 		devc->num_channels = 16;
@@ -548,6 +554,11 @@ SR_PRIV int sigma_set_samplerate(const struct sr_dev_inst *sdi, uint64_t sampler
 		devc->num_channels = 4;
 	}
 
+	/*
+	 * Derive the sample period from the sample rate as well as the
+	 * number of samples that the device will communicate within
+	 * an "event" (memory organization internal to the device).
+	 */
 	if (ret == SR_OK) {
 		devc->cur_samplerate = samplerate;
 		devc->period_ps = 1000000000000ULL / samplerate;
@@ -555,6 +566,18 @@ SR_PRIV int sigma_set_samplerate(const struct sr_dev_inst *sdi, uint64_t sampler
 		devc->state.state = SIGMA_IDLE;
 	}
 
+	/*
+	 * Support for "limit_samples" is implemented by stopping
+	 * acquisition after a corresponding period of time.
+	 * Re-calculate that period of time, in case the limit is
+	 * set first and the samplerate gets (re-)configured later.
+	 */
+	if (ret == SR_OK && devc->limit_samples) {
+		uint64_t msecs;
+		msecs = devc->limit_samples * 1000 / devc->cur_samplerate;
+		devc->limit_msec = msecs;
+	}
+
 	return ret;
 }