From debb52156c0e4d0420b18090e06db365bd757992 Mon Sep 17 00:00:00 2001
From: Jade <spacey-sooty@proton.me>
Date: Mon, 4 Nov 2024 02:37:44 +0800
Subject: [PATCH] [wpilib] Clamp sim battery voltage to 0 (#7325)

---
 .../main/native/include/frc/simulation/BatterySim.h   | 11 +++++++----
 .../edu/wpi/first/wpilibj/simulation/BatterySim.java  |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/wpilibc/src/main/native/include/frc/simulation/BatterySim.h b/wpilibc/src/main/native/include/frc/simulation/BatterySim.h
index ab79844e30c..d50ff224806 100644
--- a/wpilibc/src/main/native/include/frc/simulation/BatterySim.h
+++ b/wpilibc/src/main/native/include/frc/simulation/BatterySim.h
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <algorithm>
 #include <numeric>
 #include <span>
 
@@ -33,8 +34,9 @@ class BatterySim {
   static units::volt_t Calculate(units::volt_t nominalVoltage,
                                  units::ohm_t resistance,
                                  std::span<const units::ampere_t> currents) {
-    return nominalVoltage -
-           std::accumulate(currents.begin(), currents.end(), 0_A) * resistance;
+    return std::max(0_V, nominalVoltage - std::accumulate(currents.begin(),
+                                                          currents.end(), 0_A) *
+                                              resistance);
   }
 
   /**
@@ -52,8 +54,9 @@ class BatterySim {
   static units::volt_t Calculate(
       units::volt_t nominalVoltage, units::ohm_t resistance,
       std::initializer_list<units::ampere_t> currents) {
-    return nominalVoltage -
-           std::accumulate(currents.begin(), currents.end(), 0_A) * resistance;
+    return std::max(0_V, nominalVoltage - std::accumulate(currents.begin(),
+                                                          currents.end(), 0_A) *
+                                              resistance);
   }
 
   /**
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/BatterySim.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/BatterySim.java
index 78c988848c0..fcee31bdb3f 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/BatterySim.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/simulation/BatterySim.java
@@ -27,7 +27,7 @@ public static double calculateLoadedBatteryVoltage(
     for (var current : currents) {
       retval -= current * resistanceOhms;
     }
-    return retval;
+    return Math.max(0.0, retval);
   }
 
   /**