Fix book feedback at configured skill cap

SFALL_COMPATIBILITY.md

@@ -58,7 +58,8 @@ See [`https://sfall-team.github.io/sfall/`](https://sfall-team.github.io/sfall/)
 | Direct memory access| read_byte,short,int,string<br>write_byte,short,int,string<br>call_offset_vX | 🚫 | Not possible.  Open an issue if you need functionality not covered by other opcodes. |
 | Stats | get/set_pc_base_stat<br>get/set_pc_extra_stat<br>get/set_critter_base_stat<br>get/set_critter_extra_stat | ✅ | CE uses engine stat helpers here instead of sfall's direct proto-field behavior, so derived-stat update behavior can differ. |
 | Stats / Alter min/max | get/set_stat_min/max<br>set_pc_stat_min/max<br>set_npc_stat_min/max | not implemented | - |
-| Skills | get/set_critter_skill_points<br>get/set_available_skill_points<br>set_skill_max<br>set_critter_skill_mod<br>set_base_skill_mod<br>mod_skill_points_per_level | not implemented | - |
+| Skills | set_skill_max | ✅ | - |
+| Skills | get/set_critter_skill_points<br>get/set_available_skill_points<br>set_critter_skill_mod<br>set_base_skill_mod<br>mod_skill_points_per_level | not implemented | - |
 | Graphics | graphics_funcs_available<br>force_graphics_refresh<br>get_screen_width<br>get_screen_height<br>set_palette | implemented: only get_screen_width, get_screen_height | - |
 | Shaders | load_shader<br>free_shader<br>activate_shader<br>deactivate_shader<br>set/get_shader_* | 🚫 | likely will not implement direct compatibility
 | Perks and traits | set_perk_image<br>set_perk_*<br>set_pyromaniac_mod<br>apply_heaveho_fix<br>set_swiftlearner_mod<br>has/set_fake_perk<br>has/set_fake_trait<br>set_selectable_perk<br>set_perkbox_title<br>show/hide_real_perks<br>perk_add_mode<br>clear_selectable_perks<br>add/remove_trait<br>seq_perk_freq | not implemented | - |

sfall_testing/gl_test_skill_max.ssl

@@ -0,0 +1,38 @@
+#include "define_lite.h"
+#include "define_extra.h"
+#include "sfall.h"
+#include "test_utils.h"
+
+procedure start begin
+    variable skill_offset;
+    variable original_points;
+    variable original_value;
+    variable capped_points;
+
+    if (not game_loaded) then return;
+
+    display_msg("Testing set_skill_max...");
+    test_suite_errors := 0;
+
+    skill_offset := PROTO_CR_SKILLS + (SKILL_SMALL_GUNS * 4);
+    original_points := get_proto_data(obj_pid(dude_obj), skill_offset);
+    original_value := has_skill(dude_obj, SKILL_SMALL_GUNS);
+
+    set_skill_max(300);
+    critter_mod_skill(dude_obj, SKILL_SMALL_GUNS, 1000);
+    call assertEquals("skill raised to vanilla cap", has_skill(dude_obj, SKILL_SMALL_GUNS), 300);
+
+    capped_points := get_proto_data(obj_pid(dude_obj), skill_offset);
+    set_skill_max(200);
+    call assertEquals("existing skill clamped to 200", has_skill(dude_obj, SKILL_SMALL_GUNS), 200);
+
+    critter_mod_skill(dude_obj, SKILL_SMALL_GUNS, 1);
+    call assertEquals("skill points unchanged at cap", get_proto_data(obj_pid(dude_obj), skill_offset), capped_points);
+
+    set_skill_max(300);
+    set_proto_data(obj_pid(dude_obj), skill_offset, original_points);
+    call assertEquals("original skill restored", has_skill(dude_obj, SKILL_SMALL_GUNS), original_value);
+
+    call report_test_results("set_skill_max");
+    signal_close_game;
+end

src/proto_instance.cc

@@ -802,8 +802,17 @@ static UseItemResultCode _obj_use_book(Object* book)
             increase = 150 * increase / 100;
         }
 
+        bool increased = false;
         for (int i = 0; i < increase; i++) {
-            skillAddForce(gDude, skill);
+            if (skillAddForce(gDude, skill) != 0) {
+                break;
+            }
+
+            increased = true;
+        }
+
+        if (!increased) {
+            messageId = 801;
         }
     }
 

src/sfall_opcodes.cc

@@ -39,6 +39,7 @@
 #include "sfall_lists.h"
 #include "sfall_metarules.h"
 #include "sfall_script_hooks.h"
+#include "skill.h"
 #include "stat.h"
 #include "svga.h"
 #include "tile.h"
@@ -160,6 +161,11 @@ static void op_set_critter_extra_stat(Program* program)
     critterSetBonusStat(obj, stat, value);
 }
 
+static void op_set_skill_max(Program* program)
+{
+    skillSetMaximum(programStackPopInteger(program));
+}
+
 // get_pc_base_stat
 static void op_get_pc_base_stat(Program* program)
 {
@@ -2045,6 +2051,7 @@ void sfallOpcodesInit()
     // 0x81a0 - void set_pickpocket_max(int percentage)
     // 0x81a1 - void set_hit_chance_max(int percentage)
     // 0x81a2 - void set_skill_max(int value)
+    interpreterRegisterOpcode(0x81A2, op_set_skill_max);
     // 0x81aa - void set_xp_mod(int percentage)
     // 0x81ab - void set_perk_level_mod(int levels)
 

src/skill.cc

@@ -116,6 +116,10 @@ static int _timesSkillUsed[SKILL_COUNT][SKILLS_MAX_USES_PER_DAY];
 // 0x668070 tag_skill
 static int gTaggedSkills[NUM_TAGGED_SKILLS];
 
+// sfall's set_skill_max limit. Global scripts restore content-specific values
+// after every game reset.
+static int skillMaximum = 300;
+
 // skill.msg
 //
 // 0x668080 skill_message_file
@@ -169,6 +173,8 @@ int skillsInit()
 // 0x4AA448
 void skillsReset()
 {
+    skillMaximum = 300;
+
     for (int index = 0; index < NUM_TAGGED_SKILLS; index++) {
         gTaggedSkills[index] = -1;
     }
@@ -271,13 +277,19 @@ int skillGetValue(Object* critter, int skill)
         value += skillGetGameDifficultyModifier(skill);
     }
 
-    if (value > 300) {
-        value = 300;
+    if (value > skillMaximum) {
+        value = skillMaximum;
     }
 
     return value;
 }
 
+void skillSetMaximum(int maximum)
+{
+    // Match sfall: out-of-range values restore the vanilla ceiling.
+    skillMaximum = maximum >= 0 && maximum <= 300 ? maximum : 300;
+}
+
 // 0x4AA654
 int skillGetDefaultValue(int skill)
 {
@@ -301,7 +313,7 @@ int skillAdd(Object* obj, int skill)
     }
 
     int skillValue = skillGetValue(obj, skill);
-    if (skillValue >= 300) {
+    if (skillValue >= skillMaximum) {
         return -3;
     }
 
@@ -336,7 +348,7 @@ int skillAddForce(Object* obj, int skill)
         return -5;
     }
 
-    if (skillGetValue(obj, skill) >= 300) {
+    if (skillGetValue(obj, skill) >= skillMaximum) {
         return -3;
     }
 

src/skill.h

@@ -28,6 +28,7 @@ void skillsSetTagged(int* skills, int count);
 void skillsGetTagged(int* skills, int count);
 bool skillIsTagged(int skill);
 int skillGetValue(Object* critter, int skill);
+void skillSetMaximum(int maximum);
 int skillGetDefaultValue(int skill);
 int skillAdd(Object* critter, int skill);
 int skillAddForce(Object* critter, int skill);