segatools/board/vfd-frame.c
2024-08-23 16:30:22 +02:00

89 lines
1.7 KiB
C

#include <windows.h>
#include <assert.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#define SUPER_VERBOSE 1
#include "board/vfd-frame.h"
#include "hook/iobuf.h"
#include "util/dprintf.h"
static HRESULT vfd_frame_encode_byte(struct iobuf *dest, uint8_t byte);
/* Frame structure:
REQUEST:
[0] Sync byte (0x1A or 0x1B)
[1] Packet ID
[2...n-1] Data/payload
--- OR ---
if no sync byte is given, plain static text in the currently configured encoding is expected.
RESPONSE:
This thing never responds, unless it's VFD_CMD_GET_VERSION
*/
bool vfd_frame_sync(struct const_iobuf *src) {
return src->bytes[src->pos] == VFD_SYNC_BYTE || src->bytes[src->pos] == VFD_SYNC_BYTE2;
}
HRESULT vfd_frame_encode(
struct iobuf *dest,
const void *ptr,
size_t nbytes) {
const uint8_t *src;
uint8_t byte;
size_t i;
HRESULT hr;
assert(dest != NULL);
assert(dest->bytes != NULL || dest->nbytes == 0);
assert(dest->pos <= dest->nbytes);
assert(ptr != NULL);
src = ptr;
if (dest->pos >= dest->nbytes) {
return HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER);
}
#if SUPER_VERBOSE
dprintf("VFD: RX Buffer:\n");
#endif
for (i = 1; i < nbytes; i++) {
byte = src[i];
#if SUPER_VERBOSE
dprintf("%02x ", byte);
#endif
hr = vfd_frame_encode_byte(dest, byte);
if (FAILED(hr)) {
return hr;
}
}
#if SUPER_VERBOSE
dprintf("\n");
#endif
return hr;
}
static HRESULT vfd_frame_encode_byte(struct iobuf *dest, uint8_t byte) {
if (dest->pos + 1 > dest->nbytes) {
return HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER);
}
dest->bytes[dest->pos++] = byte;
return S_OK;
}