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- /*
- ** The pipe algo is somewhat similar to the luaL_Buffer algo, except that it uses
- ** table to store the LUAL_BUFFERSIZE byte array chunks instead of the stack.
- ** Writing is always to the last UD in the table and overflow pushes a new UD to
- ** the end of the table. Reading is always from the first UD in the table and
- ** underrun removes the first UD to shift a new one into slot 2. (Slot 1 of the
- ** table is reserved for the pipe reader function with 0 denoting no reader.)
- **
- ** Reads and writes may span multiple UD buffers and if the read spans multiple UDs
- ** then the parts are collected as strings on the Lua stack and then concatenated
- ** with a lua_concat().
- **
- ** Note that pipe tables also support the undocumented length and tostring
- ** operators for debugging puposes, so if p is a pipe then #p[i] gives the
- ** effective length of pipe slot i and printing p[i] gives its contents.
- **
- ** The pipe library also supports the automatic scheduling of a reader task. This
- ** is declared by including a Lua CB function and an optional prioirty for it to
- ** execute at in the pipe.create() call. The reader task may or may not empty the
- ** FIFO (and there is also nothing to stop the task also writing to the FIFO. The
- ** reader automatically reschedules itself if the pipe contains unread content.
- **
- ** The reader tasks may be interleaved with other tasks that write to the pipe and
- ** others that don't. Any task writing to the pipe will also trigger the posting
- ** of a read task if one is not already pending. In this way at most only one
- ** pending reader task is pending, and this prevents overrun of the task queueing
- ** system.
- **
- ** Implementation Notes:
- **
- ** - The Pipe slot 1 is used to store the Lua CB function reference of the reader
- ** task. Note that is actually an auxiliary wrapper around the supplied Lua CB
- ** function, and this wrapper also uses upvals to store internal pipe state.
- ** The remaining slots are the Userdata buffer chunks.
- **
- ** - This internal state needs to be shared with the pipe_write function, but a
- ** limitation of Lua 5.1 is that C functions cannot share upvals; to avoid this
- ** constraint, this function is also denormalised to act as the pipe_write
- ** function: if Arg1 is the pipe then its a pipe:write() otherwise its a
- ** CB wrapper.
- **
- ** Also note that the pipe module is used by the Lua VM and therefore the create
- ** read, and unread methods are exposed as directly callable C functions. (Write
- ** is available throogh pipe[1].)
- **
- ** Read the docs/modules/pipe.md documentation for a functional description.
- */
- #include "module.h"
- #include "lauxlib.h"
- #include <string.h>
- #include "platform.h"
- #define INVALID_LEN ((unsigned)-1)
- #define LUA_USE_MODULES_PIPE
- typedef struct buffer {
- int start, end;
- char buf[LUAL_BUFFERSIZE];
- } buffer_t;
- #define AT_TAIL 0x00
- #define AT_HEAD 0x01
- #define WRITING 0x02
- static buffer_t *checkPipeUD (lua_State *L, int ndx);
- static buffer_t *newPipeUD(lua_State *L, int ndx, int n);
- static int pipe_write_aux(lua_State *L);
- LROT_TABLE(pipe_meta);
- /* Validation and utility functions */
- // [-0, +0, v]
- static buffer_t *checkPipeTable (lua_State *L, int tbl, int flags) {
- int m = lua_gettop(L), n = lua_objlen(L, tbl);
- if (lua_istable(L, tbl) && lua_getmetatable(L, tbl)) {
- lua_pushrotable(L, LROT_TABLEREF(pipe_meta));/* push comparison metatable */
- if (lua_rawequal(L, -1, -2)) { /* check these match */
- buffer_t *ud;
- if (n == 1) {
- ud = (flags & WRITING) ? newPipeUD(L, tbl, 2) : NULL;
- } else {
- int i = flags & AT_HEAD ? 2 : n; /* point to head or tail of T */
- lua_rawgeti(L, tbl, i); /* and fetch UD */
- ud = checkPipeUD(L, -1);
- }
- lua_settop(L, m);
- return ud; /* and return ptr to buffer_t rec */
- }
- }
- luaL_argerror(L, tbl, "pipe table");
- return NULL; /* NORETURN avoid compiler error */
- }
- static buffer_t *checkPipeUD (lua_State *L, int ndx) { // [-0, +0, v]
- luaL_checktype(L, ndx, LUA_TUSERDATA); /* NORETURN on error */
- buffer_t *ud = lua_touserdata(L, ndx);
- if (ud && lua_getmetatable(L, ndx)) { /* Get UD and its metatable? */
- lua_pushrotable(L, LROT_TABLEREF(pipe_meta)); /* push correct metatable */
- if (lua_rawequal(L, -1, -2)) { /* Do these match? */
- lua_pop(L, 2); /* remove both metatables */
- return ud; /* and return ptr to buffer_t rec */
- }
- }
- }
- static buffer_t *newPipeUD(lua_State *L, int ndx, int n) { // [-0,+0,-]
- buffer_t *ud = (buffer_t *) lua_newuserdata(L, sizeof(buffer_t));
- lua_pushrotable(L, LROT_TABLEREF(pipe_meta)); /* push the metatable */
- lua_setmetatable(L, -2); /* set UD's metabtable to pipe_meta */
- ud->start = ud->end = 0;
- lua_rawseti(L, ndx, n); /* T[#T+1] = new UD */
- return ud; /* ud points to new T[#T] */
- }
- #define CHAR_DELIM -1
- #define CHAR_DELIM_KEEP -2
- static char getsize_delim (lua_State *L, int ndx, int *len) { // [-0, +0, v]
- char delim;
- int n;
- if( lua_type( L, ndx ) == LUA_TNUMBER ) {
- n = luaL_checkinteger( L, ndx );
- luaL_argcheck(L, n > 0, ndx, "invalid chunk size");
- delim = '\0';
- } else if (lua_isnil(L, ndx)) {
- n = CHAR_DELIM;
- delim = '\n';
- } else {
- size_t ldelim;
- const char *s = lua_tolstring( L, 2, &ldelim);
- n = ldelim == 2 && s[1] == '+' ? CHAR_DELIM_KEEP : CHAR_DELIM ;
- luaL_argcheck(L, ldelim + n == 0, ndx, "invalid delimiter");
- delim = s[0];
- }
- if (len)
- *len = n;
- return delim;
- }
- /*
- ** Read CB Initiator AND pipe_write. If arg1 == the pipe, then this is a pipe
- ** write(); otherwise it is the Lua CB wapper for the task post. This botch allows
- ** these two functions to share Upvals within the Lua 5.1 VM:
- */
- #define UVpipe lua_upvalueindex(1) // The pipe table object
- #define UVfunc lua_upvalueindex(2) // The CB's Lua function
- #define UVprio lua_upvalueindex(3) // The task priority
- #define UVstate lua_upvalueindex(4) // Pipe state;
- #define CB_NOT_USED 0
- #define CB_ACTIVE 1
- #define CB_WRITE_UPDATED 2
- #define CB_QUIESCENT 4
- /*
- ** Note that nothing precludes the Lua CB function from itself writing to the
- ** pipe and in this case this routine will call itself recursively.
- **
- ** The Lua CB itself takes the pipe object as a parameter and returns an optional
- ** boolean to force or to suppress automatic retasking if needed. If omitted,
- ** then the default is to repost if the pipe is not empty, otherwise the task
- ** chain is left to lapse.
- */
- static int pipe_write_and_read_poster (lua_State *L) {
- int state = lua_tointeger(L, UVstate);
- if (lua_rawequal(L, 1, UVpipe)) {
- /* arg1 == the pipe, so this was invoked as a pipe_write() */
- if (pipe_write_aux(L) && state && !(state & CB_WRITE_UPDATED)) {
- /*
- * if this resulted in a write and not already in a CB and not already
- * toggled the write update then post the task
- */
- state |= CB_WRITE_UPDATED;
- lua_pushinteger(L, state);
- lua_replace(L, UVstate); /* Set CB state write updated flag */
- if (state == CB_QUIESCENT | CB_WRITE_UPDATED) {
- lua_rawgeti(L, 1, 1); /* Get CB ref from pipe[1] */
- luaL_posttask(L, (int) lua_tointeger(L, UVprio)); /* and repost task */
- }
- }
- } else if (state != CB_NOT_USED) {
- /* invoked by the luaN_taskpost() so call the Lua CB */
- int repost; /* can take the values CB_WRITE_UPDATED or 0 */
- lua_pushinteger(L, CB_ACTIVE); /* CB state set to active only */
- lua_replace(L, UVstate);
- lua_pushvalue(L, UVfunc); /* Lua CB function */
- lua_pushvalue(L, UVpipe); /* pipe table */
- lua_call(L, 1, 1); /* Errors are thrown back to caller */
- /*
- * On return from the Lua CB, the task is never reposted if the pipe is empty.
- * If it is not empty then the Lua CB return status determines when reposting
- * occurs:
- * - true = repost
- * - false = don't repost
- * - nil = only repost if there has been a write update.
- */
- if (lua_isboolean(L,-1)) {
- repost = (lua_toboolean(L, -1) == true &&
- lua_objlen(L, UVpipe) > 1) ? CB_WRITE_UPDATED : 0;
- } else {
- repost = state & CB_WRITE_UPDATED;
- }
- state = CB_QUIESCENT | repost;
- lua_pushinteger(L, state); /* Update the CB state */
- lua_replace(L, UVstate);
- if (repost) {
- lua_rawgeti(L, UVpipe, 1); /* Get CB ref from pipe[1] */
- luaL_posttask(L, (int) lua_tointeger(L, UVprio)); /* and repost task */
- }
- }
- return 0;
- }
- /* Lua callable methods. Since the metatable is linked to both the pipe table */
- /* and the userdata entries the __len & __tostring functions must handle both */
- // Lua: buf = pipe.create()
- int pipe_create(lua_State *L) {
- int prio = -1;
- lua_settop(L, 2); /* fix stack sze as 2 */
- if (!lua_isnil(L, 1)) {
- luaL_checktype(L, 1, LUA_TFUNCTION); /* non-nil arg1 must be a function */
- if (lua_isnil(L, 2)) {
- prio = PLATFORM_TASK_PRIORITY_MEDIUM;
- } else {
- prio = (int) lua_tointeger(L, 2);
- luaL_argcheck(L, prio >= PLATFORM_TASK_PRIORITY_LOW &&
- prio <= PLATFORM_TASK_PRIORITY_HIGH, 2, "invalid priority");
- }
- }
- lua_createtable (L, 1, 0); /* create pipe table */
- lua_pushrotable(L, LROT_TABLEREF(pipe_meta));
- lua_setmetatable(L, -2); /* set pipe table's metabtable to pipe_meta */
- lua_pushvalue(L, -1); /* UV1: pipe object */
- lua_pushvalue(L, 1); /* UV2: CB function */
- lua_pushinteger(L, prio); /* UV3: task priority */
- lua_pushinteger(L, prio == -1 ? CB_NOT_USED : CB_QUIESCENT);
- lua_pushcclosure(L, pipe_write_and_read_poster, 4); /* post aux func as C task */
- lua_rawseti(L, -2, 1); /* and wrtie to T[1] */
- return 1; /* return the table */
- }
- // len = #pipeobj[i]
- static int pipe__len (lua_State *L) {
- if (lua_istable(L, 1)) {
- lua_pushinteger(L, lua_objlen(L, 1));
- } else {
- buffer_t *ud = checkPipeUD(L, 1);
- lua_pushinteger(L, ud->end - ud->start);
- }
- return 1;
- }
- //Lua s = pipeUD:tostring()
- static int pipe__tostring (lua_State *L) {
- if (lua_istable(L, 1)) {
- lua_pushfstring(L, "Pipe: %p", lua_topointer(L, 1));
- } else {
- buffer_t *ud = checkPipeUD(L, 1);
- lua_pushlstring(L, ud->buf + ud->start, ud->end - ud->start);
- }
- return 1;
- }
- // Lua: rec = p:read(end_or_delim) // also [-2, +1,- ]
- int pipe_read(lua_State *L) {
- buffer_t *ud = checkPipeTable(L, 1, AT_HEAD);
- int i, k=0, n;
- lua_settop(L,2);
- const char delim = getsize_delim(L, 2, &n);
- lua_pop(L,1);
- while (ud && n) {
- int want, used, avail = ud->end - ud->start;
- if (n < 0 /* one of the CHAR_DELIM flags */) {
- /* getting a delimited chunk so scan for delimiter */
- for (i = ud->start; i < ud->end && ud->buf[i] != delim; i++) {}
- /* Can't have i = ud->end and ud->buf[i] == delim so either */
- /* we've scanned full buffer avail OR we've hit a delim char */
- if (i == ud->end) {
- want = used = avail; /* case where we've scanned without a hit */
- } else {
- want = used = i + 1 - ud->start; /* case where we've hit a delim */
- if (n == CHAR_DELIM)
- want--;
- n = 0; /* force loop exit because delim found */
- }
- } else {
- want = used = (n < avail) ? n : avail;
- n -= used;
- }
- lua_pushlstring(L, ud->buf + ud->start, want); /* part we want */
- k++;
- ud->start += used;
- if (ud->start == ud->end) {
- /* shift the pipe array down overwriting T[1] */
- int nUD = lua_objlen(L, 1);
- for (i = 2; i < nUD; i++) { /* for i = 2, nUD-1 */
- lua_rawgeti(L, 1, i+1); lua_rawseti(L, 1, i); /* T[i] = T[i+1] */
- }
- lua_pushnil(L); lua_rawseti(L, 1, nUD--); /* T[n] = nil */
- if (nUD>1) {
- lua_rawgeti(L, 1, 2);
- ud = checkPipeUD(L, -1);
- lua_pop(L, 1);
- } else {
- ud = NULL;
- }
- }
- }
- if (k)
- lua_concat(L, k);
- else
- lua_pushnil(L);
- return 1;
- }
- // Lua: buf:unread(some_string)
- int pipe_unread(lua_State *L) {
- size_t l = INVALID_LEN;
- const char *s = lua_tolstring(L, 2, &l);
- if (l==0)
- return 0;
- luaL_argcheck(L, l != INVALID_LEN, 2, "must be a string");
- buffer_t *ud = checkPipeTable(L, 1, AT_HEAD | WRITING);
- do {
- int used = ud->end - ud->start;
- int lrem = LUAL_BUFFERSIZE-used;
- if (used == LUAL_BUFFERSIZE) {
- /* If the current UD is full insert a new UD at T[2] */
- int i, nUD = lua_objlen(L, 1);
- for (i = nUD; i > 0; i--) { /* for i = nUD-1,1,-1 */
- lua_rawgeti(L, 1, i); lua_rawseti(L, 1, i+1); /* T[i+1] = T[i] */
- }
- ud = newPipeUD(L, 1, 1);
- used = 0; lrem = LUAL_BUFFERSIZE;
- } else if (ud->start < l) {
- /* If the unread can't fit it before the start then shift content to end */
- memmove(ud->buf + lrem,
- ud->buf + ud->start, used); /* must be memmove not cpy */
- ud->start = lrem; ud->end = LUAL_BUFFERSIZE;
- }
- if (l <= (unsigned )lrem)
- break;
- /* If we've got here then the remaining string is strictly longer than the */
- /* remaining buffer space, so top off the buffer before looping around again */
- l -= lrem;
- memcpy(ud->buf, s + l, lrem);
- ud->start = 0;
- } while(1);
- /* Copy any residual tail to the UD buffer. Note that this is l>0 and */
- ud->start -= l;
- memcpy(ud->buf + ud->start, s, l);
- return 0;
- }
- // Lua: buf:write(some_string)
- static int pipe_write_aux(lua_State *L) {
- size_t l = INVALID_LEN;
- const char *s = lua_tolstring(L, 2, &l);
- //dbg_printf("pipe write(%u): %s", l, s);
- if (l==0)
- return false;
- luaL_argcheck(L, l != INVALID_LEN, 2, "must be a string");
- buffer_t *ud = checkPipeTable(L, 1, AT_TAIL | WRITING);
- do {
- int used = ud->end - ud->start;
- if (used == LUAL_BUFFERSIZE) {
- /* If the current UD is full insert a new UD at T[end] */
- ud = newPipeUD(L, 1, lua_objlen(L, 1)+1);
- used = 0;
- } else if (LUAL_BUFFERSIZE - ud->end < l) {
- /* If the write can't fit it at the end then shift content to the start */
- memmove(ud->buf, ud->buf + ud->start, used); /* must be memmove not cpy */
- ud->start = 0; ud->end = used;
- }
- int lrem = LUAL_BUFFERSIZE-used;
- if (l <= (unsigned )lrem)
- break;
- /* If we've got here then the remaining string is longer than the buffer */
- /* space left, so top off the buffer before looping around again */
- memcpy(ud->buf + ud->end, s, lrem);
- ud->end += lrem;
- l -= lrem;
- s += lrem;
- } while(1);
- /* Copy any residual tail to the UD buffer. Note that this is l>0 and */
- memcpy(ud->buf + ud->end, s, l);
- ud->end += l;
- return true;
- }
- // Lua: fread = pobj:reader(1400) -- or other number
- // fread = pobj:reader('\n') -- or other delimiter (delim is stripped)
- // fread = pobj:reader('\n+') -- or other delimiter (delim is retained)
- #define TBL lua_upvalueindex(1)
- #define N lua_upvalueindex(2)
- static int pipe_read_aux(lua_State *L) {
- lua_settop(L, 0); /* ignore args since we use upvals instead */
- lua_pushvalue(L, TBL);
- lua_pushvalue(L, N);
- return pipe_read(L);
- }
- static int pipe_reader(lua_State *L) {
- lua_settop(L,2);
- checkPipeTable (L, 1,AT_HEAD);
- getsize_delim(L, 2, NULL);
- lua_pushcclosure(L, pipe_read_aux, 2); /* return (closure, nil, table) */
- return 1;
- }
- LROT_BEGIN(pipe_funcs, NULL, 0)
- LROT_FUNCENTRY( __len, pipe__len )
- LROT_FUNCENTRY( __tostring, pipe__tostring )
- LROT_FUNCENTRY( read, pipe_read )
- LROT_FUNCENTRY( reader, pipe_reader )
- LROT_FUNCENTRY( unread, pipe_unread )
- LROT_END(pipe_funcs, NULL, 0)
- /* Using a index func is needed because the write method is at pipe[1] */
- static int pipe__index(lua_State *L) {
- lua_settop(L,2);
- const char *k=lua_tostring(L,2);
- if(!strcmp(k,"write")){
- lua_rawgeti(L, 1, 1);
- } else {
- lua_pushrotable(L, LROT_TABLEREF(pipe_funcs));
- lua_replace(L, 1);
- lua_rawget(L, 1);
- }
- return 1;
- }
- LROT_BEGIN(pipe_meta, NULL, LROT_MASK_INDEX)
- LROT_FUNCENTRY( __index, pipe__index)
- LROT_FUNCENTRY( __len, pipe__len )
- LROT_FUNCENTRY( __tostring, pipe__tostring )
- LROT_END(pipe_meta, NULL, LROT_MASK_INDEX)
- LROT_BEGIN(pipe, NULL, 0)
- LROT_FUNCENTRY( create, pipe_create )
- LROT_END(pipe, NULL, 0)
- NODEMCU_MODULE(PIPE, "pipe", pipe, NULL);
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