diff options
Diffstat (limited to 'stm32f091/backlog.c')
| -rw-r--r-- | stm32f091/backlog.c | 41 |
1 files changed, 27 insertions, 14 deletions
diff --git a/stm32f091/backlog.c b/stm32f091/backlog.c index 3f21924..926ccad 100644 --- a/stm32f091/backlog.c +++ b/stm32f091/backlog.c @@ -2,33 +2,46 @@ #include "backlog.h" -ws_s_backlog_database* WS_G_BACKLOG_DATABASE = NULL; +ws_s_backlog_database* g_ws_backlog_database = NULL; void ws_backlog_alloc(uint16_t record_amt) { - WS_G_BACKLOG_DATABASE = malloc(sizeof(ws_s_backlog_database) + sizeof(ws_s_backlog_record) * record_amt); - WS_G_BACKLOG_DATABASE->buffer_size = record_amt; - WS_G_BACKLOG_DATABASE->buffer_start = 0; - WS_G_BACKLOG_DATABASE->buffer_end = 0; + g_ws_backlog_database = malloc(sizeof(ws_s_backlog_database) + sizeof(ws_s_backlog_record) * record_amt); + g_ws_backlog_database->buffer_size = record_amt; + g_ws_backlog_database->buffer_start = 0; + g_ws_backlog_database->buffer_end = 0; } void ws_backlog_add_record(ws_s_backlog_record record) { static uint16_t id = 0; - WS_G_BACKLOG_DATABASE->records[WS_G_BACKLOG_DATABASE->buffer_end].id = id++; - WS_G_BACKLOG_DATABASE->records[WS_G_BACKLOG_DATABASE->buffer_end].sens_atm_pressure = record.sens_atm_pressure; - WS_G_BACKLOG_DATABASE->records[WS_G_BACKLOG_DATABASE->buffer_end].sens_humidity = record.sens_humidity; - WS_G_BACKLOG_DATABASE->records[WS_G_BACKLOG_DATABASE->buffer_end].sens_temperature = record.sens_temperature; + g_ws_backlog_database->records[g_ws_backlog_database->buffer_end].id = id++; + g_ws_backlog_database->records[g_ws_backlog_database->buffer_end].sens_atm_pressure = record.sens_atm_pressure; + g_ws_backlog_database->records[g_ws_backlog_database->buffer_end].sens_humidity = record.sens_humidity; + g_ws_backlog_database->records[g_ws_backlog_database->buffer_end].sens_temperature = record.sens_temperature; // shift buffer start/end - WS_G_BACKLOG_DATABASE->buffer_end = (WS_G_BACKLOG_DATABASE->buffer_end + 1) % WS_G_BACKLOG_DATABASE->buffer_size; - if (WS_G_BACKLOG_DATABASE->buffer_end == WS_G_BACKLOG_DATABASE->buffer_start) - WS_G_BACKLOG_DATABASE->buffer_start = (WS_G_BACKLOG_DATABASE->buffer_start + 1) % WS_G_BACKLOG_DATABASE->buffer_size; + g_ws_backlog_database->buffer_end = (g_ws_backlog_database->buffer_end + 1) % g_ws_backlog_database->buffer_size; + if (g_ws_backlog_database->buffer_end == g_ws_backlog_database->buffer_start) + g_ws_backlog_database->buffer_start = (g_ws_backlog_database->buffer_start + 1) % g_ws_backlog_database->buffer_size; } ws_s_backlog_record* ws_backlog_get_record(uint16_t record_index) { - return &WS_G_BACKLOG_DATABASE->records[record_index]; + return &g_ws_backlog_database->records[record_index]; } ws_s_backlog_record* ws_backlog_get_last_record(uint16_t record_offset) { - return ws_backlog_get_record((WS_G_BACKLOG_DATABASE->buffer_end - record_offset - 1) % WS_G_BACKLOG_DATABASE->buffer_size); + return ws_backlog_get_record((g_ws_backlog_database->buffer_end - record_offset - 1) % g_ws_backlog_database->buffer_size); +} + +static uint16_t mod(uint16_t a, uint16_t b) { + uint16_t m = a % b; + return m < 0 ? (b < 0) ? m - b : m + b : m; +} + +uint16_t ws_backlog_get_record_count() { + // add buffer_size to the result of the modulo operation if it's result is negative + // (only works when buffer_size is less than 2^15) + // this is a consequence of the way in which c handles negative numbers in modulo operations + int16_t mod = (g_ws_backlog_database->buffer_end - g_ws_backlog_database->buffer_start) % g_ws_backlog_database->buffer_size; + return mod < 0 ? mod + g_ws_backlog_database->buffer_size : mod; } |