From e732965529ce3b29de2d211349c033f4b5724a23 Mon Sep 17 00:00:00 2001
From: Helmut Eller <eller.helmut@gmail.com>
Date: Fri, 16 Aug 2024 08:28:35 +0200
Subject: [PATCH 2/4] Add gen_params to igc_params.

* src/igc.h (struct igc_gen_param): New.
(struct igc_params): Add gen_params field.
* src/emacs.c (parse_igc_gen_params): New.
(parse_igc_param): Use it.
* src/igc.c (make_arena): Use igc_params to configure the generation
chain.
---
 src/emacs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 src/igc.c   | 11 +++++++++--
 src/igc.h   | 12 ++++++++++++
 3 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/src/emacs.c b/src/emacs.c
index ced3f723919..b2d12b61967 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -736,6 +736,45 @@ argmatch (char **argv, int argc, const char *sstr, const char *lstr,
 }
 
 #ifdef HAVE_MPS
+static void
+parse_igc_gen_params (const char *string, struct igc_params *params)
+{
+  size_t count = 0;
+  struct igc_gen_param *array = NULL;
+  for (const char *s = string;;)
+    {
+      int n = 0;
+      size_t capacity, mortality;
+      if ((sscanf (s, "%zuk%zu%%%n", &capacity, &mortality, &n) == 2)
+	  && mortality <= 100)
+	{
+	  struct igc_gen_param p = { .capacity = capacity,
+				     .mortality = (double)mortality / 100.0 };
+	  count++;
+	  array = xrealloc (array, sizeof (array[0]) * count);
+	  array[count - 1] = p;
+	  if (s[n] == ',')
+	    {
+	      s = &s[n + 1];
+	      continue;
+	    }
+	  else if (s[n] == '\0')
+	    {
+	      params->gen_params.dflt = false;
+	      params->gen_params.gen_count = count;
+	      params->gen_params.gen_params = array;
+	      return;
+	    }
+	  else
+	    break;
+	}
+      else
+	break;
+    }
+  fprintf (stderr, "Invalid value gen_params: %s\n", string);
+  exit (1);
+}
+
 static void
 parse_igc_param (const char *val, struct igc_params *params)
 {
@@ -746,6 +785,11 @@ parse_igc_param (const char *val, struct igc_params *params)
       params->pause_time.dflt = false;
       return;
     }
+
+  const char *key = "gen_params=";
+  if (strncmp (val, key, strlen (key)) == 0)
+    return parse_igc_gen_params (val + strlen (key), params);
+
   fprintf (stderr, "Invalid igc_param: %s\n", val);
   exit (1);
 }
diff --git a/src/igc.c b/src/igc.c
index c294eae747e..77f897bfdca 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -4463,8 +4463,15 @@ make_arena (struct igc *gc, const struct igc_params *params)
   MPS_ARGS_END (args);
   IGC_CHECK_RES (res);
 
-  mps_gen_param_s gens[] = { { 128000, 0.8 }, { 5 * 128000, 0.4 } };
-  res = mps_chain_create (&gc->chain, gc->arena, ARRAYELTS (gens), gens);
+  mps_gen_param_s dflt_gens[] = { { 128000, 0.8 }, { 5 * 128000, 0.4 } };
+  mps_gen_param_s *gens = dflt_gens;
+  size_t ngens = ARRAYELTS (dflt_gens);
+  if (!params->gen_params.dflt)
+    {
+      ngens = params->gen_params.gen_count;
+      gens = (mps_gen_param_s *)params->gen_params.gen_params;
+    }
+  res = mps_chain_create (&gc->chain, gc->arena, ngens, gens);
   IGC_CHECK_RES (res);
 }
 
diff --git a/src/igc.h b/src/igc.h
index 586db8ce77f..716069adceb 100644
--- a/src/igc.h
+++ b/src/igc.h
@@ -60,6 +60,12 @@ #define EMACS_IGC_H
 
 #ifdef HAVE_MPS
 
+struct igc_gen_param
+{
+  size_t capacity;	  /* in kilobytes */
+  double mortality;	  /* initial estimate; valid values in [0..1] */
+};
+
 struct igc_params
 {
   struct
@@ -67,6 +73,12 @@ #define EMACS_IGC_H
     bool dflt;
     double seconds; /* in seconds; valid values in [0..INF] */
   } pause_time;
+  struct
+  {
+    bool dflt;
+    size_t gen_count;
+    struct igc_gen_param *gen_params;
+  } gen_params;
 };
 
 void igc_break (void);
-- 
2.39.2