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#include <mpack.h>
#include <stdio.h>
// MIN() macro
#include <sys/param.h>
// TODO: check if this works on pico as well
#include "puzbusv1.h"
bool pb_read(struct pb_msg* target, char* buf, size_t buf_sz) {
// remaining bytes to be read to target->data; this is the only variable that
// needs to persist between buffer blocks, and is therefore static
static size_t rdata = 0;
// 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: This approach will crash and burn when target->addr can be read
// and target->length is past the end of the current buffer block. 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.
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 == 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;
}
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