diff options
Diffstat (limited to 'types-ring.c')
| -rw-r--r-- | types-ring.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/types-ring.c b/types-ring.c new file mode 100644 index 0000000..6cceea1 --- /dev/null +++ b/types-ring.c @@ -0,0 +1,193 @@ +/* See LICENSE file for copyright and license details. */ +#include "types-ring.h" + +#include <stdlib.h> +#include <string.h> + + +/** + * Initialise a ring buffer + * + * @param this The ring buffer + */ +void +ring_initialise(struct ring *restrict this) +{ + this->start = 0; + this->end = 0; + this->size = 0; + this->buffer = NULL; +} + + +#if defined(__clang__) +# pragma GCC diagnostic push +# pragma GCC diagnostic ignored "-Wcast-align" +#endif + + +/** + * Marshal a ring buffer + * + * @param this The ring buffer + * @param buf Output buffer for the marshalled data, + * `NULL` to only measure how large buffer + * is needed + * @return The number of marshalled bytes + */ +size_t +ring_marshal(const struct ring *restrict this, void *restrict buf) +{ + size_t off = 0, n = this->end - this->start; + char *bs = buf; + + if (bs) + *(size_t *)&bs[off] = n; + off += sizeof(size_t); + + if (bs) + memcpy(&bs[off], this->buffer + this->start, n); + off += n; + + return off; +} + + +/** + * Unmarshal a ring buffer + * + * @param this Output parameter for the ring buffer + * @param buf Buffer with the marshalled data + * @return The number of unmarshalled bytes, 0 on error + */ +size_t +ring_unmarshal(struct ring *restrict this, const void *restrict buf) +{ + size_t off = 0; + const char *bs = buf; + + ring_initialise(this); + + this->size = this->end = *(const size_t *)&bs[off]; + off += sizeof(size_t); + + if (this->end > 0) { + this->buffer = malloc(this->end); + if (!this->buffer) + return 0; + + memcpy(this->buffer, bs + off, this->end); + off += this->end; + } + + return off; +} + + +#if defined(__clang__) +# pragma GCC diagnostic pop +#endif + + +/** + * Append data to a ring buffer + * + * @param this The ring buffer + * @param data The new data + * @param n The number of bytes in `data` + * @return Zero on success, -1 on error + */ +int +ring_push(struct ring *restrict this, void *restrict data, size_t n) +{ + size_t used = 0; + char *restrict new; + + if (this->start == this->end) { + if (this->buffer) + used = this->size; + } else if (this->start > this->end) { + used = this->size - this->start + this->end; + } else { + used = this->start - this->end; + } + + if (used + n > this->size) { + new = malloc(used + n); + if (!new) + return -1; + if (this->buffer) { + if (this->start < this->end) { + memcpy(new, this->buffer + this->start, this->end - this->start); + } else { + memcpy(new, this->buffer + this->start, this->size - this->start); + memcpy(new + this->size - this->start, this->buffer, this->end); + } + } + memcpy(new + used, data, n); + this->buffer = new; + this->start = 0; + this->end = used + n; + this->size = used + n; + } else if (this->start >= this->end || this->end + n <= this->size) { + memcpy(&this->buffer[this->end], data, n); + this->end += n; + } else { + memcpy(&this->buffer[this->end], data, this->size - this->end); + data = &((char *)data)[this->size - this->end]; + n -= this->size - this->end; + memcpy(this->buffer, data, n); + this->end = n; + } + + return 0; +} + + +/** + * Get queued data from a ring buffer + * + * It can take up to two calls (with `ring_pop` between) + * to get all queued data + * + * @param this The ring buffer + * @param n Output parameter for the length + * of the returned segment + * @return The beginning of the queued data, + * `NULL` if there is nothing more + */ +void * +ring_peek(struct ring *restrict this, size_t *restrict n) +{ + if (!this->buffer) { + *n = 0; + return NULL; + } + + if (this->start < this->end) + *n = this->end - this->start; + else + *n = this->size - this->start; + return this->buffer + this->start; +} + + +/** + * Dequeue data from a ring bubber + * + * @param this The ring buffer + * @param n The number of bytes to dequeue + */ +void +ring_pop(struct ring *restrict this, size_t n) +{ + this->start += n; + this->start %= this->size; + if (this->start == this->end) { + free(this->buffer); + this->start = 0; + this->end = 0; + this->size = 0; + this->buffer = NULL; + } +} |