From f52699a8bf609e813eb31ab9df5ab130d44ac9a2 Mon Sep 17 00:00:00 2001
From: vhaudiquet <vhaudiquet343@hotmail.fr>
Date: Sun, 8 Oct 2023 17:42:44 +0200
Subject: [PATCH] Multithread gdbstub and execution, with cont/halt

---
 src/cpu/rv32cpu.c     |  9 +++++++++
 src/cpu/rv32cpu.h     |  7 +++++++
 src/gdbstub/gdbstub.c | 12 +++++++++++-
 src/main.c            |  1 +
 4 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/cpu/rv32cpu.c b/src/cpu/rv32cpu.c
index 1e9afc1..8cc68c1 100644
--- a/src/cpu/rv32cpu.c
+++ b/src/cpu/rv32cpu.c
@@ -42,6 +42,7 @@ void cpu_init()
 {
 	cpu0 = calloc(1, sizeof(rv32_cpu_t));
 	pthread_mutex_init(&cpu0_mutex, 0);
+	pthread_cond_init(&cpu0->sim_condition, 0);
 	cpu0->regs.zero = 0;
 }
 
@@ -651,6 +652,9 @@ void cpu_loop(rv32_cpu_t* cpu)
 		pthread_mutex_lock(&cpu0_mutex);
 		pthread_mutex_lock(&memory_mutex);
 
+		while(!cpu->sim_ticks_left)
+			pthread_cond_wait(&cpu0->sim_condition, &cpu0_mutex);
+
 		// Fetch
 		raw_instruction_t raw_instruction;
 		if(cpu->pc > memory_size - 4)
@@ -675,6 +679,11 @@ void cpu_loop(rv32_cpu_t* cpu)
 
 		cpu->pc += 4;
 
+		// Update simulation data
+		cpu->sim_ticks_done++;
+		if(cpu->sim_ticks_left != (-1))
+			cpu->sim_ticks_left--;
+
 		// Let go of cpu and memory mutex
 		pthread_mutex_unlock(&cpu0_mutex);
 		pthread_mutex_unlock(&memory_mutex);
diff --git a/src/cpu/rv32cpu.h b/src/cpu/rv32cpu.h
index 74846e0..01465a9 100644
--- a/src/cpu/rv32cpu.h
+++ b/src/cpu/rv32cpu.h
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <pthread.h>
+#include <stdlib.h>
 
 /*
 * This is a structure encoding for the registers of
@@ -184,8 +185,14 @@ typedef struct RV32_CPU_REGS
 
 typedef struct RV32_CPU
 {
+	// CPU values
     rv32_cpu_regs_t regs;
     uint32_t pc;
+
+	// Simulation data
+	ssize_t sim_ticks_left; // -1 : simulate forever
+	size_t sim_ticks_done;
+	pthread_cond_t sim_condition;
 } rv32_cpu_t;
 
 extern rv32_cpu_t* cpu0;
diff --git a/src/gdbstub/gdbstub.c b/src/gdbstub/gdbstub.c
index 8bfa5e0..d556dd2 100644
--- a/src/gdbstub/gdbstub.c
+++ b/src/gdbstub/gdbstub.c
@@ -24,6 +24,7 @@ typedef struct sockaddr sockaddr_t;
 
 socket_t gdbstub_server_socket;
 socket_t gdb_socket;
+pthread_t gdbstub_thread;
 
 void gdbstub_thread_gdb();
 static void gdbstub_handle_ctrlc();
@@ -159,7 +160,7 @@ void gdbstub_wait_for_connection()
 
 	gdb_socket = c_socket;
 
-	gdbstub_thread_gdb();
+	pthread_create(&gdbstub_thread, 0, (void*) gdbstub_thread_gdb, 0);
 }
 
 void gdbstub_thread_gdb()
@@ -285,6 +286,8 @@ void gdbstub_thread_gdb()
 		{
 			// s : single-step
 
+			// TODO : Implement that correctly
+
 			// Send back halt reason
 			// Halt Reason : Signal 05 (SIGTRAP)
 			char* resp = "S05";
@@ -298,6 +301,10 @@ void gdbstub_thread_gdb()
 			send(gdb_socket, "+", 1, 0);
 
 			// Continue simulation
+			pthread_mutex_lock(&cpu0_mutex);
+			cpu0->sim_ticks_left = -1;
+			pthread_mutex_unlock(&cpu0_mutex);
+			pthread_cond_signal(&cpu0->sim_condition);
 		}
 		else gdbstub_send_unsupported();
 	}
@@ -310,6 +317,9 @@ void gdbstub_thread_gdb()
 static void gdbstub_handle_ctrlc()
 {
 	// Halt the simulation
+	pthread_mutex_lock(&cpu0_mutex);
+	cpu0->sim_ticks_left = 0;
+	pthread_mutex_unlock(&cpu0_mutex);
 
 	// Send back halt signal to gdb
 	// Halt Reason : Signal 05 (SIGTRAP)
diff --git a/src/main.c b/src/main.c
index eb7b64e..4bdae12 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,6 +28,7 @@ int main(int argc, char** argv)
     }
 
     // CPU simulation : create cpu0 thread
+    if(!gdbstub) cpu0->sim_ticks_left = -1; // Simulate forever
     pthread_t cpu0_thread;
     pthread_create(&cpu0_thread, 0, (void*) cpu_loop, cpu0);