1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
#include <mpack.h>
#include <stdio.h>
// MIN() macro
#include <sys/param.h>
// TODO: check if this works on pico as well
#include "puzbusv1.h"
/**
* \brief Remaining bytes to be read to target->data
*
* This is the only variable that needs to persist between buffer blocks. It is
* declared in the global scope to allow resetting using the \c pb_read_reset()
* function.
*
* \note \p rdata may be reset by calling \c pb_read_reset()
*/
static size_t rdata = 0;
int pb_read(struct pb_msg* target, char* buf, size_t buf_sz) {
// a new reader is used per buffer block passed to this function
mpack_reader_t reader;
mpack_reader_init_data(&reader, buf, buf_sz);
// at start of message
if (rdata == 0) {
// NOTE: The entire start of a message needs to be readable from the buffer
// at this point. When target->addr can be read and target->length is past
// the end of the current buffer block, this function will crash and burn.
// This is a highly unlikely scenario, as pb_read is called for each chunk
// of a TCP frame, and frames (should) include only one puzzle bus message.
// The check here is kind of optional.
if (buf_sz < 4) return -1;
target->addr = mpack_expect_u16(&reader);
target->length = rdata = mpack_expect_bin(&reader);
target->data = (char*) malloc(target->length);
}
// continue reading chunks of target->data until the amount of bytes
// specified in target->length
size_t to_read = MIN(mpack_reader_remaining(&reader, NULL), rdata);
char* data = target->data + target->length - rdata; // 'ol pointer arithmetic
mpack_read_bytes(&reader, data, to_read);
rdata -= to_read;
// if rdata = 0, the message was completely read
return rdata;
}
void pb_read_reset() {
rdata = 0;
}
bool pb_write(struct pb_msg* target, char** buf, size_t* buf_sz) {
mpack_writer_t writer;
mpack_writer_init_growable(&writer, buf, buf_sz);
mpack_write_u16(&writer, target->addr);
mpack_write_bin(&writer, target->data, target->length);
// finish writing
return mpack_writer_destroy(&writer) == mpack_ok;
}
|