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author | Lorry Tar Creator <lorry-tar-importer@lorry> | 2016-04-22 04:38:07 +0000 |
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committer | Lorry Tar Creator <lorry-tar-importer@lorry> | 2016-04-22 04:38:07 +0000 |
commit | 28ef1abc10cfbc2c3d2747c008eb2300858d0426 (patch) | |
tree | 41208fb8f393e6cb6cc8f939623ad47a0db17876 /lib/i-ring.h | |
download | grep-tarball-28ef1abc10cfbc2c3d2747c008eb2300858d0426.tar.gz |
Diffstat (limited to 'lib/i-ring.h')
-rw-r--r-- | lib/i-ring.h | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/lib/i-ring.h b/lib/i-ring.h new file mode 100644 index 0000000..0064b65 --- /dev/null +++ b/lib/i-ring.h @@ -0,0 +1,44 @@ +/* definitions for a simple ring buffer + Copyright (C) 2006, 2009-2016 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#include <stdbool.h> +#include "verify.h" + +enum { I_RING_SIZE = 4 }; +verify (1 <= I_RING_SIZE); + +/* When ir_empty is true, the ring is empty. + Otherwise, ir_data[B..F] are defined, where B..F is the contiguous + range of indices, modulo I_RING_SIZE, from back to front, inclusive. + Undefined elements of ir_data are always set to ir_default_val. + Popping from an empty ring aborts. + Pushing onto a full ring returns the displaced value. + An empty ring has F==B and ir_empty == true. + A ring with one entry still has F==B, but now ir_empty == false. */ +struct I_ring +{ + int ir_data[I_RING_SIZE]; + int ir_default_val; + unsigned int ir_front; + unsigned int ir_back; + bool ir_empty; +}; +typedef struct I_ring I_ring; + +void i_ring_init (I_ring *ir, int ir_default_val); +int i_ring_push (I_ring *ir, int val); +int i_ring_pop (I_ring *ir); +bool i_ring_empty (I_ring const *ir) _GL_ATTRIBUTE_PURE; |