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Introduce support for callback functions #140

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2014c85
Move msg_type_t to modbus.h and rename to modbus_msg_type_t
mhei Sep 28, 2013
2bf681a
Introduce callback functions for length calculations
mhei Sep 28, 2013
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15 changes: 2 additions & 13 deletions src/modbus-private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,18 +44,6 @@ typedef enum {
_MODBUS_BACKEND_TYPE_TCP
} modbus_backend_type_t;

/*
* ---------- Request Indication ----------
* | Client | ---------------------->| Server |
* ---------- Confirmation Response ----------
*/
typedef enum {
/* Request message on the server side */
MSG_INDICATION,
/* Request message on the client side */
MSG_CONFIRMATION
} msg_type_t;

/* This structure reduces the number of params in functions and so
* optimizes the speed of execution (~ 37%). */
typedef struct _sft {
Expand Down Expand Up @@ -98,13 +86,14 @@ struct _modbus {
int error_recovery;
struct timeval response_timeout;
struct timeval byte_timeout;
modbus_callback_t callback[MODBUS_CALLBACK_MAX];
const modbus_backend_t *backend;
void *backend_data;
};

void _modbus_init_common(modbus_t *ctx);
void _error_print(modbus_t *ctx, const char *context);
int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);
int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, modbus_msg_type_t msg_type);

#ifndef HAVE_STRLCPY
size_t strlcpy(char *dest, const char *src, size_t dest_size);
Expand Down
4 changes: 2 additions & 2 deletions src/modbus-rtu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -306,15 +306,15 @@ static int _modbus_rtu_receive(modbus_t *ctx, uint8_t *req)
modbus_rtu_t *ctx_rtu = ctx->backend_data;

if (ctx_rtu->confirmation_to_ignore) {
_modbus_receive_msg(ctx, req, MSG_CONFIRMATION);
_modbus_receive_msg(ctx, req, MODBUS_MSG_CONFIRMATION);
/* Ignore errors and reset the flag */
ctx_rtu->confirmation_to_ignore = FALSE;
rc = 0;
if (ctx->debug) {
printf("Confirmation to ignore\n");
}
} else {
rc = _modbus_receive_msg(ctx, req, MSG_INDICATION);
rc = _modbus_receive_msg(ctx, req, MODBUS_MSG_INDICATION);
if (rc == 0) {
/* The next expected message is a confirmation to ignore */
ctx_rtu->confirmation_to_ignore = TRUE;
Expand Down
2 changes: 1 addition & 1 deletion src/modbus-tcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,7 @@ static ssize_t _modbus_tcp_send(modbus_t *ctx, const uint8_t *req, int req_lengt
}

static int _modbus_tcp_receive(modbus_t *ctx, uint8_t *req) {
return _modbus_receive_msg(ctx, req, MSG_INDICATION);
return _modbus_receive_msg(ctx, req, MODBUS_MSG_INDICATION);
}

static ssize_t _modbus_tcp_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length) {
Expand Down
63 changes: 45 additions & 18 deletions src/modbus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -107,6 +107,24 @@ static void _sleep_response_timeout(modbus_t *ctx)
#endif
}

/* Assign a callback function pointer to context */
int modbus_register_callback(modbus_t *ctx, modbus_callback_type_t cb_type, modbus_callback_t cb)
{
if (ctx == NULL) {
errno = EINVAL;
return -1;
}

/* prevent abuse */
if (cb_type >= MODBUS_CALLBACK_MAX) {
errno = EINVAL;
return -1;
}

ctx->callback[cb_type] = cb;
return 0;
}

int modbus_flush(modbus_t *ctx)
{
int rc;
Expand Down Expand Up @@ -246,12 +264,12 @@ int modbus_send_raw_request(modbus_t *ctx, uint8_t *raw_req, int raw_req_length)
*/

/* Computes the length to read after the function received */
static uint8_t compute_meta_length_after_function(int function,
msg_type_t msg_type)
static uint8_t compute_meta_length_after_function(modbus_t *ctx, int function,
modbus_msg_type_t msg_type)
{
int length;

if (msg_type == MSG_INDICATION) {
if (msg_type == MODBUS_MSG_INDICATION) {
if (function <= MODBUS_FC_WRITE_SINGLE_REGISTER) {
length = 4;
} else if (function == MODBUS_FC_WRITE_MULTIPLE_COILS ||
Expand All @@ -266,7 +284,7 @@ static uint8_t compute_meta_length_after_function(int function,
length = 0;
}
} else {
/* MSG_CONFIRMATION */
/* MODBUS_MSG_CONFIRMATION */
switch (function) {
case MODBUS_FC_WRITE_SINGLE_COIL:
case MODBUS_FC_WRITE_SINGLE_REGISTER:
Expand All @@ -282,17 +300,21 @@ static uint8_t compute_meta_length_after_function(int function,
}
}

if (ctx->callback[MODBUS_CALLBACK_COMPUTE_META_LENGTH]) {
ctx->callback[MODBUS_CALLBACK_COMPUTE_META_LENGTH](ctx, function, msg_type, &length);
}

return length;
}

/* Computes the length to read after the meta information (address, count, etc) */
static int compute_data_length_after_meta(modbus_t *ctx, uint8_t *msg,
msg_type_t msg_type)
modbus_msg_type_t msg_type)
{
int function = msg[ctx->backend->header_length];
int length;

if (msg_type == MSG_INDICATION) {
if (msg_type == MODBUS_MSG_INDICATION) {
switch (function) {
case MODBUS_FC_WRITE_MULTIPLE_COILS:
case MODBUS_FC_WRITE_MULTIPLE_REGISTERS:
Expand All @@ -315,6 +337,10 @@ static int compute_data_length_after_meta(modbus_t *ctx, uint8_t *msg,
}
}

if (ctx->callback[MODBUS_CALLBACK_COMPUTE_DATA_LENGTH]) {
ctx->callback[MODBUS_CALLBACK_COMPUTE_DATA_LENGTH](ctx, msg, msg_type, &length);
}

length += ctx->backend->checksum_length;

return length;
Expand All @@ -334,7 +360,7 @@ static int compute_data_length_after_meta(modbus_t *ctx, uint8_t *msg,
- read() or recv() error codes
*/

int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type)
int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, modbus_msg_type_t msg_type)
{
int rc;
fd_set rset;
Expand All @@ -345,7 +371,7 @@ int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type)
_step_t step;

if (ctx->debug) {
if (msg_type == MSG_INDICATION) {
if (msg_type == MODBUS_MSG_INDICATION) {
printf("Waiting for a indication...\n");
} else {
printf("Waiting for a confirmation...\n");
Expand All @@ -362,7 +388,7 @@ int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type)
step = _STEP_FUNCTION;
length_to_read = ctx->backend->header_length + 1;

if (msg_type == MSG_INDICATION) {
if (msg_type == MODBUS_MSG_INDICATION) {
/* Wait for a message, we don't know when the message will be
* received */
p_tv = NULL;
Expand Down Expand Up @@ -428,6 +454,7 @@ int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type)
case _STEP_FUNCTION:
/* Function code position */
length_to_read = compute_meta_length_after_function(
ctx,
msg[ctx->backend->header_length],
msg_type);
if (length_to_read != 0) {
Expand Down Expand Up @@ -494,7 +521,7 @@ int modbus_receive_confirmation(modbus_t *ctx, uint8_t *rsp)
return -1;
}

return _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
return _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
}

static int check_confirmation(modbus_t *ctx, uint8_t *req,
Expand Down Expand Up @@ -1106,7 +1133,7 @@ static int read_io_status(modbus_t *ctx, int function,
int offset;
int offset_end;

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1215,7 +1242,7 @@ static int read_registers(modbus_t *ctx, int function, int addr, int nb,
int offset;
int i;

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1306,7 +1333,7 @@ static int write_single(modbus_t *ctx, int function, int addr, int value)
/* Used by write_bit and write_register */
uint8_t rsp[MAX_MESSAGE_LENGTH];

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1391,7 +1418,7 @@ int modbus_write_bits(modbus_t *ctx, int addr, int nb, const uint8_t *src)
if (rc > 0) {
uint8_t rsp[MAX_MESSAGE_LENGTH];

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1441,7 +1468,7 @@ int modbus_write_registers(modbus_t *ctx, int addr, int nb, const uint16_t *src)
if (rc > 0) {
uint8_t rsp[MAX_MESSAGE_LENGTH];

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1474,7 +1501,7 @@ int modbus_mask_write_register(modbus_t *ctx, int addr, uint16_t and_mask, uint1
/* Used by write_bit and write_register */
uint8_t rsp[MAX_MESSAGE_LENGTH];

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1544,7 +1571,7 @@ int modbus_write_and_read_registers(modbus_t *ctx,
if (rc > 0) {
int offset;

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down Expand Up @@ -1588,7 +1615,7 @@ int modbus_report_slave_id(modbus_t *ctx, int max_dest, uint8_t *dest)
int offset;
uint8_t rsp[MAX_MESSAGE_LENGTH];

rc = _modbus_receive_msg(ctx, rsp, MSG_CONFIRMATION);
rc = _modbus_receive_msg(ctx, rsp, MODBUS_MSG_CONFIRMATION);
if (rc == -1)
return -1;

Expand Down
23 changes: 23 additions & 0 deletions src/modbus.h
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Original file line number Diff line number Diff line change
Expand Up @@ -219,6 +219,29 @@ MODBUS_API int modbus_reply(modbus_t *ctx, const uint8_t *req,
MODBUS_API int modbus_reply_exception(modbus_t *ctx, const uint8_t *req,
unsigned int exception_code);

/*
* ---------- Request Indication ----------
* | Client | ---------------------->| Server |
* ---------- Confirmation Response ----------
*/
typedef enum {
/* Request message on the server side */
MODBUS_MSG_INDICATION,
/* Request message on the client side */
MODBUS_MSG_CONFIRMATION
} modbus_msg_type_t;

typedef enum
{
MODBUS_CALLBACK_COMPUTE_META_LENGTH,
MODBUS_CALLBACK_COMPUTE_DATA_LENGTH,
MODBUS_CALLBACK_MAX
} modbus_callback_type_t;

typedef int (*modbus_callback_t)(modbus_t *ctx, ...);

MODBUS_API int modbus_register_callback(modbus_t *ctx, modbus_callback_type_t cb_type, modbus_callback_t cb);

/**
* UTILS FUNCTIONS
**/
Expand Down