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Diffstat (limited to 'ecos/packages/net/tcpip/current/src/lib/select.c')
| -rw-r--r-- | ecos/packages/net/tcpip/current/src/lib/select.c | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/ecos/packages/net/tcpip/current/src/lib/select.c b/ecos/packages/net/tcpip/current/src/lib/select.c new file mode 100644 index 0000000..9316913 --- /dev/null +++ b/ecos/packages/net/tcpip/current/src/lib/select.c @@ -0,0 +1,209 @@ +//========================================================================== +// +// lib/select.c +// +// 'select()' system call +// +//========================================================================== +// ####BSDALTCOPYRIGHTBEGIN#### +// ------------------------------------------- +// Portions of this software may have been derived from OpenBSD +// or other sources, and if so are covered by the appropriate copyright +// and license included herein. +// ------------------------------------------- +// ####BSDALTCOPYRIGHTEND#### +//========================================================================== +//#####DESCRIPTIONBEGIN#### +// +// Author(s): gthomas +// Contributors: gthomas +// Date: 2000-01-10 +// Purpose: +// Description: eCos implementation of 'select()' system call +// +// +//####DESCRIPTIONEND#### +// +//========================================================================== + +#include <sys/param.h> +#include <cyg/io/file.h> +#include <cyg/kernel/kapi.h> +#include <sys/select.h> +#include <sys/bsdselect.h> + +static cyg_flag_t select_flag; +static cyg_bool select_flag_init = false; +#define SELECT_WAKE 0x01 +#define SELECT_ABORT 0x02 + +// +// Private function which does all the work for 'select()' +// +static int +_cyg_select(int nfd, fd_set *in, fd_set *out, fd_set *ex, + struct timeval *tv, cyg_bool_t abortable) +{ + int fd, mode, num, ticks; + struct file *fp; + fd_set in_res, out_res, ex_res; // Result sets + fd_set *selection[3], *result[3]; + cyg_tick_count_t now, then; + int mode_type[] = {FREAD, FWRITE, 0}; + cyg_flag_value_t flag, wait_flag; + + // Note: since this is called by application programs, it needs no protection + if (!select_flag_init) { + select_flag_init = true; + cyg_flag_init(&select_flag); + } + wait_flag = SELECT_WAKE; + if (abortable) wait_flag |= SELECT_ABORT; + FD_ZERO(&in_res); + FD_ZERO(&out_res); + FD_ZERO(&ex_res); + // Set up sets + selection[0] = in; result[0] = &in_res; + selection[1] = out; result[1] = &out_res; + selection[2] = ex; result[2] = &ex_res; + // Compute end time + if (tv) { + now = cyg_current_time(); + ticks = (tv->tv_sec * 100) + (tv->tv_usec / 10000); + then = now + ticks; + } else { + then = 0; // Compiler warnings :-( + ticks = 0; + } + // Scan sets for possible I/O until something found, timeout or error. + while (true) { + num = 0; // Total file descriptors "ready" + + cyg_scheduler_lock(); // Scan the list atomically wrt electing to sleep + + for (mode = 0; mode < 3; mode++) { + if (selection[mode]) { + for (fd = 0; fd < nfd; fd++) { + if (FD_ISSET(fd, selection[mode])) { + if (getfp(fd, &fp)) { + cyg_scheduler_unlock(); // return. + errno = EBADF; + return -1; + } + if ((*fp->f_ops->fo_select)(fp, mode_type[mode])) { + FD_SET(fd, result[mode]); + num++; + } + } + } + } + } + if (num) { + + cyg_scheduler_unlock(); // Happy, about to return. + + // Found something, update user's sets + if (in) { + memcpy(in, &in_res, sizeof(in_res)); + } + if (out) { + memcpy(out, &out_res, sizeof(out_res)); + } + if (ex) { + memcpy(ex, &ex_res, sizeof(ex_res)); + } + return num; + } + // Nothing found, see if we want to wait + if (tv) { + if (ticks == 0) { + // Special case of "poll" + cyg_scheduler_unlock(); // About to return. + return 0; + } + flag = cyg_flag_timed_wait(&select_flag, wait_flag, + CYG_FLAG_WAITMODE_OR, + then); + } else { + // Wait forever (until something happens) + flag = cyg_flag_wait(&select_flag, wait_flag, + CYG_FLAG_WAITMODE_OR); + } + + cyg_scheduler_unlock(); // waited atomically + + if (flag & SELECT_ABORT) { + errno = EINTR; + return -1; + } + if (!flag) { + return 0; // meaning no activity, ergo timeout occurred + } + } + errno = ENOSYS; + return -1; +} + +// +// This function is called by the lower layers to record the +// fact that a particular 'select' event is being requested. +// +void +selrecord(void *selector, struct selinfo *info) +{ + // Unused by this implementation +} + +// +// This function is called to indicate that a 'select' event +// may have occurred. +// +void +selwakeup(struct selinfo *info) +{ + // Need these ops to be atomic to make sure the clear occurs - + // otherwise a higher prio thread could hog the CPU when its fds are + // not ready, but the flag is (already) set, or set for someone else. + cyg_scheduler_lock(); + cyg_flag_setbits(&select_flag, SELECT_WAKE); + cyg_flag_maskbits(&select_flag, 0 ); // clear all + cyg_scheduler_unlock(); +} + +// +// The public function used by 'normal' programs. This interface does not allow +// the 'select()' to be externally interrupted. +// +int +select(int nfd, fd_set *in, fd_set *out, fd_set *ex, + struct timeval *tv) +{ + return _cyg_select(nfd, in, out, ex, tv, false); +} + +// +// The public function used by programs which wish to allow interruption, +// using the 'cyg_select_abort()' function below. +// +int +cyg_select_with_abort(int nfd, fd_set *in, fd_set *out, fd_set *ex, + struct timeval *tv) +{ + return _cyg_select(nfd, in, out, ex, tv, true); +} + +// +// This function can be called by the user to forceably abort any +// current selects. +// +void +cyg_select_abort(void) +{ + // See comments in selwakeup()... + cyg_scheduler_lock(); + cyg_flag_setbits(&select_flag, SELECT_ABORT); + cyg_flag_maskbits(&select_flag, 0 ); + cyg_scheduler_unlock(); +} + + |