Revise SCPI read API to allow backend-independent data handling.

[libsigrok.git] / hardware / common / scpi_tcp.c

diff --git a/hardware/common/scpi_tcp.c b/hardware/common/scpi_tcp.c
index af2db140661ce99c04d77f79f92872723c4de8c5..44557937ef06af77a88d333973544f57c56587f5 100644 (file)
--- a/hardware/common/scpi_tcp.c
+++ b/hardware/common/scpi_tcp.c
@@ -39,10 +39,16 @@
 
 #define LOG_PREFIX "scpi_tcp"
 
+#define LENGTH_BYTES 4
+
 struct scpi_tcp {
        char *address;
        char *port;
        int socket;
+       char length_buf[LENGTH_BYTES];
+       int length_bytes_read;
+       int response_length;
+       int response_bytes_read;
 };
 
 SR_PRIV int scpi_tcp_open(void *priv)
@@ -129,40 +135,40 @@ SR_PRIV int scpi_tcp_send(void *priv, const char *command)
        return SR_OK;
 }
 
-SR_PRIV int scpi_tcp_receive(void *priv, char **scpi_response)
+SR_PRIV int scpi_tcp_read_begin(void *priv)
 {
        struct scpi_tcp *tcp = priv;
-       GString *response;
-       char buf[256];
-       int len;
 
-       response = g_string_sized_new(1024);
-
-       len = recv(tcp->socket, buf, sizeof(buf), 0);
-
-       if (len < 0) {
-               sr_err("Receive error: %s", strerror(errno));
-               g_string_free(response, TRUE);
-               return SR_ERR;
-       }
-
-       response = g_string_append_len(response, buf + 4, len - 4);
-
-       *scpi_response = response->str;
-
-       sr_dbg("SCPI response received (length %d): '%.50s'",
-              response->len, response->str);
-
-       g_string_free(response, FALSE);
+       tcp->response_bytes_read = 0;
+       tcp->length_bytes_read = 0;
 
        return SR_OK;
 }
 
-SR_PRIV int scpi_tcp_read(void *priv, char *buf, int maxlen)
+SR_PRIV int scpi_tcp_read_data(void *priv, char *buf, int maxlen)
 {
        struct scpi_tcp *tcp = priv;
        int len;
 
+       if (tcp->length_bytes_read < LENGTH_BYTES) {
+               len = recv(tcp->socket, tcp->length_buf + tcp->length_bytes_read,
+                               LENGTH_BYTES - tcp->length_bytes_read, 0);
+               if (len < 0) {
+                       sr_err("Receive error: %s", strerror(errno));
+                       return SR_ERR;
+               }
+
+               tcp->length_bytes_read += len;
+
+               if (tcp->length_bytes_read < LENGTH_BYTES)
+                       return 0;
+               else
+                       tcp->response_length = RL32(tcp->length_buf);
+       }
+
+       if (tcp->response_bytes_read >= tcp->response_length)
+               return SR_ERR;
+
        len = recv(tcp->socket, buf, maxlen, 0);
 
        if (len < 0) {
@@ -170,9 +176,19 @@ SR_PRIV int scpi_tcp_read(void *priv, char *buf, int maxlen)
                return SR_ERR;
        }
 
+       tcp->response_bytes_read += len;
+
        return len;
 }
 
+SR_PRIV int scpi_tcp_read_complete(void *priv)
+{
+       struct scpi_tcp *tcp = priv;
+
+       return (tcp->length_bytes_read == LENGTH_BYTES &&
+                       tcp->response_bytes_read >= tcp->response_length);
+}
+
 SR_PRIV int scpi_tcp_close(void *priv)
 {
        struct scpi_tcp *tcp = priv;
@@ -209,8 +225,9 @@ SR_PRIV struct sr_scpi_dev_inst *scpi_tcp_dev_inst_new(const char *address,
        scpi->source_add = scpi_tcp_source_add;
        scpi->source_remove = scpi_tcp_source_remove;
        scpi->send = scpi_tcp_send;
-       scpi->receive = scpi_tcp_receive;
-       scpi->read = scpi_tcp_read;
+       scpi->read_begin = scpi_tcp_read_begin;
+       scpi->read_data = scpi_tcp_read_data;
+       scpi->read_complete = scpi_tcp_read_complete;
        scpi->close = scpi_tcp_close;
        scpi->free = scpi_tcp_free;
        scpi->priv = tcp;