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-rw-r--r--util-src/ringbuffer.c214
1 files changed, 214 insertions, 0 deletions
diff --git a/util-src/ringbuffer.c b/util-src/ringbuffer.c
new file mode 100644
index 00000000..831b1fe2
--- /dev/null
+++ b/util-src/ringbuffer.c
@@ -0,0 +1,214 @@
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <lua.h>
+#include <lauxlib.h>
+
+typedef struct {
+ size_t rpos; /* read position */
+ size_t wpos; /* write position */
+ size_t alen; /* allocated size */
+ size_t blen; /* current content size */
+ char buffer[];
+} ringbuffer;
+
+char readchar(ringbuffer *b) {
+ b->blen--;
+ return b->buffer[(b->rpos++) % b->alen];
+}
+
+void writechar(ringbuffer *b, char c) {
+ b->blen++;
+ b->buffer[(b->wpos++) % b->alen] = c;
+}
+
+/* make sure position counters stay within the allocation */
+void modpos(ringbuffer *b) {
+ b->rpos = b->rpos % b->alen;
+ b->wpos = b->wpos % b->alen;
+}
+
+int find(ringbuffer *b, const char *s, int l) {
+ size_t i, j;
+ int m;
+
+ if(b->rpos == b->wpos) { /* empty */
+ return 0;
+ }
+
+ for(i = 0; i <= b->blen - l; i++) {
+ if(b->buffer[(b->rpos + i) % b->alen] == *s) {
+ m = 1;
+
+ for(j = 1; j < l; j++)
+ if(b->buffer[(b->rpos + i + j) % b->alen] != s[j]) {
+ m = 0;
+ break;
+ }
+
+ if(m) {
+ return i + l;
+ }
+ }
+ }
+
+ return 0;
+}
+
+int rb_find(lua_State *L) {
+ size_t l, m;
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ const char *s = luaL_checklstring(L, 2, &l);
+ m = find(b, s, l);
+
+ if(m > 0) {
+ lua_pushinteger(L, m);
+ return 1;
+ }
+
+ return 0;
+}
+
+int rb_read(lua_State *L) {
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ int r = luaL_checkinteger(L, 2);
+ int peek = lua_toboolean(L, 3);
+
+ if(r > b->blen) {
+ lua_pushnil(L);
+ return 1;
+ }
+
+ if((b->rpos + r) > b->alen) {
+ lua_pushlstring(L, &b->buffer[b->rpos], b->alen - b->rpos);
+ lua_pushlstring(L, b->buffer, r - (b->alen - b->rpos));
+ lua_concat(L, 2);
+ } else {
+ lua_pushlstring(L, &b->buffer[b->rpos], r);
+ }
+
+ if(!peek) {
+ b->blen -= r;
+ b->rpos += r;
+ modpos(b);
+ }
+
+ return 1;
+}
+
+int rb_readuntil(lua_State *L) {
+ size_t l, m;
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ const char *s = luaL_checklstring(L, 2, &l);
+ m = find(b, s, l);
+
+ if(m > 0) {
+ lua_settop(L, 1);
+ lua_pushinteger(L, m);
+ return rb_read(L);
+ }
+
+ return 0;
+}
+
+int rb_write(lua_State *L) {
+ size_t l, w = 0;
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ const char *s = luaL_checklstring(L, 2, &l);
+
+ /* Does `l` bytes fit? */
+ if((l + b->blen) > b->alen) {
+ lua_pushnil(L);
+ return 1;
+ }
+
+ while(l-- > 0) {
+ writechar(b, *s++);
+ w++;
+ }
+
+ modpos(b);
+
+ lua_pushinteger(L, w);
+
+ return 1;
+}
+
+int rb_tostring(lua_State *L) {
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ lua_pushfstring(L, "ringbuffer: %p %d/%d", b, b->blen, b->alen);
+ return 1;
+}
+
+int rb_length(lua_State *L) {
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ lua_pushinteger(L, b->blen);
+ return 1;
+}
+
+int rb_size(lua_State *L) {
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ lua_pushinteger(L, b->alen);
+ return 1;
+}
+
+int rb_free(lua_State *L) {
+ ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt");
+ lua_pushinteger(L, b->alen - b->blen);
+ return 1;
+}
+
+int rb_new(lua_State *L) {
+ size_t size = luaL_optinteger(L, 1, sysconf(_SC_PAGESIZE));
+ ringbuffer *b = lua_newuserdata(L, sizeof(ringbuffer) + size);
+
+ b->rpos = 0;
+ b->wpos = 0;
+ b->alen = size;
+ b->blen = 0;
+
+ luaL_getmetatable(L, "ringbuffer_mt");
+ lua_setmetatable(L, -2);
+
+ return 1;
+}
+
+int luaopen_util_ringbuffer(lua_State *L) {
+#if (LUA_VERSION_NUM > 501)
+ luaL_checkversion(L);
+#endif
+
+ if(luaL_newmetatable(L, "ringbuffer_mt")) {
+ lua_pushcfunction(L, rb_tostring);
+ lua_setfield(L, -2, "__tostring");
+ lua_pushcfunction(L, rb_length);
+ lua_setfield(L, -2, "__len");
+
+ lua_newtable(L); /* __index */
+ {
+ lua_pushcfunction(L, rb_find);
+ lua_setfield(L, -2, "find");
+ lua_pushcfunction(L, rb_read);
+ lua_setfield(L, -2, "read");
+ lua_pushcfunction(L, rb_readuntil);
+ lua_setfield(L, -2, "readuntil");
+ lua_pushcfunction(L, rb_write);
+ lua_setfield(L, -2, "write");
+ lua_pushcfunction(L, rb_size);
+ lua_setfield(L, -2, "size");
+ lua_pushcfunction(L, rb_length);
+ lua_setfield(L, -2, "length");
+ lua_pushcfunction(L, rb_free);
+ lua_setfield(L, -2, "free");
+ }
+ lua_setfield(L, -2, "__index");
+ }
+
+ lua_newtable(L);
+ lua_pushcfunction(L, rb_new);
+ lua_setfield(L, -2, "new");
+ return 1;
+}