rdtech-um: rephrase checksum verification routines

[libsigrok.git] / src / hardware / rdtech-um / protocol.c

diff --git a/src/hardware/rdtech-um/protocol.c b/src/hardware/rdtech-um/protocol.c
index 3a196c76070ce14202c49e306b3482672c70ff2f..6c56e245faa5f21576a1354e9fc21c65e8f14d2c 100644 (file)
--- a/src/hardware/rdtech-um/protocol.c
+++ b/src/hardware/rdtech-um/protocol.c
@@ -58,15 +58,21 @@ static const struct binary_analog_channel rdtech_um25c_channels[] = {
        ALL_ZERO,
 };
 
-static int poll_csum_fff1(char buf[], int len)
+static gboolean csum_ok_fff1(const uint8_t *buf, size_t len)
 {
+       uint16_t csum_recv;
+
        if (len != UM_POLL_LEN)
-               return 0;
-       else
-               return RB16(&buf[len - 2]) == 0xFFF1;
+               return FALSE;
+
+       csum_recv = read_u16be(&buf[len - sizeof(uint16_t)]);
+       if (csum_recv != 0xfff1)
+               return FALSE;
+
+       return TRUE;
 }
 
-static int poll_csum_um34c(char buf[], int len)
+static gboolean csum_ok_um34c(const uint8_t *buf, size_t len)
 {
        static const int positions[] = {
                1, 3, 7, 9, 15, 17, 19, 23, 31, 39, 41, 45, 49, 53,
@@ -74,25 +80,26 @@ static int poll_csum_um34c(char buf[], int len)
                111, 113, 119, 121, 127,
        };
 
-       unsigned int i;
-       uint8_t csum;
+       size_t i;
+       uint8_t csum_calc, csum_recv;
 
        if (len != UM_POLL_LEN)
-               return 0;
+               return FALSE;
 
-       csum = 0;
+       csum_calc = 0;
        for (i = 0; i < ARRAY_SIZE(positions); i++)
-               csum ^= buf[positions[i]];
-       if (csum != (uint8_t)buf[len - 1])
-               return 0;
+               csum_calc ^= buf[positions[i]];
+       csum_recv = read_u8(&buf[len - sizeof(uint8_t)]);
+       if (csum_recv != csum_calc)
+               return FALSE;
 
-       return 1;
+       return TRUE;
 }
 
 static const struct rdtech_um_profile um_profiles[] = {
-       { "UM24C", RDTECH_UM24C, rdtech_default_channels, &poll_csum_fff1, },
-       { "UM25C", RDTECH_UM25C, rdtech_um25c_channels, &poll_csum_fff1, },
-       { "UM34C", RDTECH_UM34C, rdtech_default_channels, &poll_csum_um34c, },
+       { "UM24C", RDTECH_UM24C, rdtech_default_channels, csum_ok_fff1, },
+       { "UM25C", RDTECH_UM25C, rdtech_um25c_channels, csum_ok_fff1, },
+       { "UM34C", RDTECH_UM34C, rdtech_default_channels, csum_ok_um34c, },
 };
 
 static const struct rdtech_um_profile *find_profile(uint16_t id)
@@ -110,7 +117,7 @@ SR_PRIV const struct rdtech_um_profile *rdtech_um_probe(struct sr_serial_dev_ins
 {
        const struct rdtech_um_profile *p;
        uint8_t request;
-       char buf[RDTECH_UM_BUFSIZE];
+       uint8_t buf[RDTECH_UM_BUFSIZE];
        int len;
 
        request = UM_CMD_POLL;
@@ -132,7 +139,7 @@ SR_PRIV const struct rdtech_um_profile *rdtech_um_probe(struct sr_serial_dev_ins
                return NULL;
        }
 
-       if (!p->poll_csum(buf, len)) {
+       if (!p->csum_ok(buf, len)) {
                sr_err("Probe response contains illegal checksum or end marker.\n");
                return NULL;
        }
@@ -167,9 +174,9 @@ static void handle_poll_data(const struct sr_dev_inst *sdi)
        GSList *ch;
 
        devc = sdi->priv;
-       sr_spew("Received poll packet (len: %d).", devc->buflen);
+       sr_spew("Received poll packet (len: %zu).", devc->buflen);
        if (devc->buflen != UM_POLL_LEN) {
-               sr_err("Unexpected poll packet length: %i", devc->buflen);
+               sr_err("Unexpected poll packet length: %zu", devc->buflen);
                return;
        }
 
@@ -208,7 +215,7 @@ static void recv_poll_data(struct sr_dev_inst *sdi, struct sr_serial_dev_inst *s
                }
        }
 
-       if (devc->buflen == UM_POLL_LEN && p->poll_csum(devc->buf, devc->buflen))
+       if (devc->buflen == UM_POLL_LEN && p->csum_ok(devc->buf, devc->buflen))
                handle_poll_data(sdi);
        else
                sr_warn("Skipping packet with illegal checksum / end marker.");