litex/build/sim/core/modules/clocker/clocker.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <json-c/json.h>
   5 #include "error.h"
   6 #include "modules.h"
   7
   8 struct session_s {
   9   char *clk;
  10   char *name;
  11   uint32_t freq_hz;
  12   uint16_t phase_deg;
  13 };
  14
  15 static int litex_sim_module_pads_get( struct pad_s *pads, char *name, void **signal)
  16 {
  17   int ret = RC_OK;
  18   void *sig=NULL;
  19   int i;
  20
  21   if(!pads || !name || !signal) {
  22     ret=RC_INVARG;
  23     goto out;
  24   }
  25
  26   i = 0;
  27   while(pads[i].name) {
  28     if(!strcmp(pads[i].name, name))
  29     {
  30       sig=(void*)pads[i].signal;
  31       break;
  32     }
  33     i++;
  34   }
  35
  36 out:
  37   *signal=sig;
  38   return ret;
  39 }
  40
  41 static int clocker_parse_args(struct session_s *s, const char *args)
  42 {
  43   int ret = RC_OK;
  44   json_object *args_json = NULL;
  45   json_object *freq_json = NULL;
  46   json_object *phase_json = NULL;
  47
  48   args_json = json_tokener_parse(args);
  49   if (!args_json) {
  50     ret = RC_JSERROR;
  51     fprintf(stderr, "[clocker] Could not parse args: %s\n", args);
  52     goto out;
  53   }
  54
  55   if(!json_object_object_get_ex(args_json, "freq_hz", &freq_json))
  56   {
  57     ret = RC_JSERROR;
  58     fprintf(stderr, "[clocker] \"freq_hz\" not found in args: %s\n", json_object_to_json_string(args_json));
  59     goto out;
  60   }
  61
  62   if(!json_object_object_get_ex(args_json, "phase_deg", &phase_json))
  63   {
  64     ret = RC_JSERROR;
  65     fprintf(stderr, "[clocker] \"phase_deg\" not found in args: %s\n", json_object_to_json_string(args_json));
  66     goto out;
  67   }
  68
  69   s->freq_hz = json_object_get_int64(freq_json);
  70   s->phase_deg = json_object_get_int64(phase_json);
  71
  72   if (s->freq_hz == 0) {
  73     ret = RC_JSERROR;
  74     fprintf(stderr, "[clocker] \"freq_hz\" must be different than 0\n");
  75     goto out;
  76   }
  77
  78   if (s->phase_deg >= 360) {
  79     ret = RC_JSERROR;
  80     fprintf(stderr, "[clocker] \"phase_deg\" must be in range [0, 360)\n");
  81     goto out;
  82   }
  83 out:
  84   if(args_json) json_object_put(args_json);
  85   return ret;
  86 }
  87
  88 static int clocker_start()
  89 {
  90   printf("[clocker] loaded\n");
  91   return RC_OK;
  92 }
  93
  94 static int clocker_new(void **sess, char *args)
  95 {
  96   int ret = RC_OK;
  97
  98   struct session_s *s=NULL;
  99
 100   if(!sess) {
 101     ret = RC_INVARG;
 102     goto out;
 103   }
 104
 105   s=(struct session_s*)malloc(sizeof(struct session_s));
 106   if(!s) {
 107     ret=RC_NOENMEM;
 108     goto out;
 109   }
 110   memset(s, 0, sizeof(struct session_s));
 111
 112   clocker_parse_args(s, args);
 113 out:
 114   *sess=(void*)s;
 115   return ret;
 116 }
 117
 118 static int clocker_add_pads(void *sess, struct pad_list_s *plist)
 119 {
 120   int ret = RC_OK;
 121   struct session_s *s = (struct session_s*)sess;
 122   struct pad_s *pads;
 123
 124   if(!sess || !plist) {
 125     ret = RC_INVARG;
 126     goto out;
 127   }
 128   pads = plist->pads;
 129
 130   ret = litex_sim_module_pads_get(pads, plist->name, (void**)&s->clk);
 131   if (ret != RC_OK) {
 132     goto out;
 133   }
 134
 135   s->name = plist->name;
 136   *s->clk=0;
 137   printf("[clocker] %s: freq_hz=%u, phase_deg=%u\n", s->name, s->freq_hz, s->phase_deg);
 138 out:
 139   return ret;
 140 }
 141
 142 static int clocker_tick(void *sess, uint64_t time_ps)
 143 {
 144   static const uint64_t ps_in_sec = 1000000000000ull;
 145   struct session_s *s = (struct session_s*) sess;
 146
 147   uint64_t period_ps = ps_in_sec / s->freq_hz;
 148   uint64_t phase_shift_ps = period_ps * s->phase_deg / 360;
 149
 150   // phase-shifted time relative to start of current period
 151   uint64_t rel_time_ps = (time_ps - phase_shift_ps) % period_ps;
 152   if (rel_time_ps < (period_ps/2)) {
 153     *s->clk = 1;
 154   } else {
 155     *s->clk = 0;
 156   }
 157
 158   return 0;
 159 }
 160
 161 static struct ext_module_s ext_mod = {
 162   "clocker",
 163   clocker_start,
 164   clocker_new,
 165   clocker_add_pads,
 166   NULL,
 167   clocker_tick
 168 };
 169
 170 int litex_sim_ext_module_init(int (*register_module)(struct ext_module_s *))
 171 {
 172   int ret = RC_OK;
 173   ret = register_module(&ext_mod);
 174   return ret;
 175 }