Revert "remove time.c and system.c"

This reverts commit bd2c5afb02.

init.c

@@ -12,6 +12,8 @@ void pic_init_bool(pic_state *);
 void pic_init_pair(pic_state *);
 void pic_init_port(pic_state *);
 void pic_init_number(pic_state *);
+void pic_init_time(pic_state *);
+void pic_init_system(pic_state *);
 void pic_init_file(pic_state *);
 void pic_init_proc(pic_state *);
 void pic_init_symbol(pic_state *);
@@ -51,6 +53,8 @@ pic_init_core(pic_state *pic)
     pic_init_pair(pic); DONE;
     pic_init_port(pic); DONE;
     pic_init_number(pic); DONE;
+    pic_init_time(pic); DONE;
+    pic_init_system(pic); DONE;
     pic_init_file(pic); DONE;
     pic_init_proc(pic); DONE;
     pic_init_symbol(pic); DONE;

system.c

@@ -0,0 +1,136 @@
+/**
+ * See Copyright Notice in picrin.h
+ */
+
+#include <stdlib.h>
+
+#include "picrin.h"
+#include "picrin/string.h"
+#include "picrin/pair.h"
+#include "picrin/cont.h"
+
+static pic_value
+pic_system_cmdline(pic_state *pic)
+{
+  pic_value v = pic_nil_value();
+  int i;
+
+  pic_get_args(pic, "");
+
+  for (i = 0; i < pic->argc; ++i) {
+    size_t ai = pic_gc_arena_preserve(pic);
+
+    v = pic_cons(pic, pic_obj_value(pic_str_new_cstr(pic, pic->argv[i])), v);
+    pic_gc_arena_restore(pic, ai);
+  }
+
+  return pic_reverse(pic, v);
+}
+
+static pic_value
+pic_system_exit(pic_state *pic)
+{
+  pic_value v;
+  int argc, status = EXIT_SUCCESS;
+
+  argc = pic_get_args(pic, "|o", &v);
+  if (argc == 1) {
+    switch (pic_type(v)) {
+    case PIC_TT_FLOAT:
+      status = (int)pic_float(v);
+      break;
+    case PIC_TT_INT:
+      status = pic_int(v);
+      break;
+    default:
+      break;
+    }
+  }
+
+  pic_close(pic);
+
+  exit(status);
+}
+
+static pic_value
+pic_system_emergency_exit(pic_state *pic)
+{
+  pic_value v;
+  int argc, status = EXIT_FAILURE;
+
+  argc = pic_get_args(pic, "|o", &v);
+  if (argc == 1) {
+    switch (pic_type(v)) {
+    case PIC_TT_FLOAT:
+      status = (int)pic_float(v);
+      break;
+    case PIC_TT_INT:
+      status = pic_int(v);
+      break;
+    default:
+      break;
+    }
+  }
+
+  _Exit(status);
+}
+
+static pic_value
+pic_system_getenv(pic_state *pic)
+{
+  char *str, *val;
+
+  pic_get_args(pic, "z", &str);
+
+  val = getenv(str);
+
+  if (val == NULL)
+    return pic_nil_value();
+  else
+    return pic_obj_value(pic_str_new_cstr(pic, val));
+}
+
+static pic_value
+pic_system_getenvs(pic_state *pic)
+{
+  char **envp;
+  pic_value data = pic_nil_value();
+  size_t ai = pic_gc_arena_preserve(pic);
+
+  pic_get_args(pic, "");
+
+  if (! pic->envp) {
+    return pic_nil_value();
+  }
+
+  for (envp = pic->envp; *envp; ++envp) {
+    pic_str *key, *val;
+    int i;
+
+    for (i = 0; (*envp)[i] != '='; ++i)
+      ;
+
+    key = pic_str_new(pic, *envp, i);
+    val = pic_str_new_cstr(pic, getenv(pic_str_cstr(key)));
+
+    /* push */
+    data = pic_acons(pic, pic_obj_value(key), pic_obj_value(val), data);
+
+    pic_gc_arena_restore(pic, ai);
+    pic_gc_protect(pic, data);
+  }
+
+  return data;
+}
+
+void
+pic_init_system(pic_state *pic)
+{
+  pic_deflibrary (pic, "(scheme process-context)") {
+    pic_defun(pic, "command-line", pic_system_cmdline);
+    pic_defun(pic, "exit", pic_system_exit);
+    pic_defun(pic, "emergency-exit", pic_system_emergency_exit);
+    pic_defun(pic, "get-environment-variable", pic_system_getenv);
+    pic_defun(pic, "get-environment-variables", pic_system_getenvs);
+  }
+}

time.c

@@ -0,0 +1,49 @@
+/**
+ * See Copyright Notice in picrin.h
+ */
+
+#include <time.h>
+
+#include "picrin.h"
+
+#define UTC_TAI_DIFF 35
+
+static pic_value
+pic_current_second(pic_state *pic)
+{
+  time_t t;
+
+  pic_get_args(pic, "");
+
+  time(&t);
+  return pic_float_value((double)t + UTC_TAI_DIFF);
+}
+
+static pic_value
+pic_current_jiffy(pic_state *pic)
+{
+  clock_t c;
+
+  pic_get_args(pic, "");
+
+  c = clock();
+  return pic_int_value(c);
+}
+
+static pic_value
+pic_jiffies_per_second(pic_state *pic)
+{
+  pic_get_args(pic, "");
+
+  return pic_int_value(CLOCKS_PER_SEC);
+}
+
+void
+pic_init_time(pic_state *pic)
+{
+  pic_deflibrary (pic, "(scheme time)") {
+    pic_defun(pic, "current-second", pic_current_second);
+    pic_defun(pic, "current-jiffy", pic_current_jiffy);
+    pic_defun(pic, "jiffies-per-second", pic_jiffies_per_second);
+  }
+}