From d7e684ad915ccd971b2b1354264d94522bb85029 Mon Sep 17 00:00:00 2001
From: vhaudiquet <vhaudiquet343@hotmail.fr>
Date: Wed, 11 Oct 2023 19:48:01 +0200
Subject: [PATCH] Added basic SBI support

---
 src/cpu/instruction.h |  2 ++
 src/cpu/rv32cpu.c     |  3 ++-
 src/devices/sbi/sbi.c | 27 +++++++++++++++++++++++++++
 src/devices/sbi/sbi.h | 11 +++++++++++
 src/main.c            |  2 +-
 5 files changed, 43 insertions(+), 2 deletions(-)
 create mode 100644 src/devices/sbi/sbi.c
 create mode 100644 src/devices/sbi/sbi.h

diff --git a/src/cpu/instruction.h b/src/cpu/instruction.h
index accadf9..234555c 100644
--- a/src/cpu/instruction.h
+++ b/src/cpu/instruction.h
@@ -97,6 +97,8 @@
 #define IMM_ECALL 0x0
 #define IMM_EBREAK 0x1
 /* RISC-V Privileged Instructions */
+#define IMM_SRET 0x102
+#define IMM_MRET 0x302
 #define FUNC7_SFENCEVMA 0x9
 #define FUNC7_WFI 0x8
 #define FUNC7_SINVALVMA 0x11
diff --git a/src/cpu/rv32cpu.c b/src/cpu/rv32cpu.c
index ae8bdd3..3c2e8ba 100644
--- a/src/cpu/rv32cpu.c
+++ b/src/cpu/rv32cpu.c
@@ -1,6 +1,7 @@
 #include "rv32cpu.h"
 #include "instruction.h"
 #include "csr.h"
+#include "devices/sbi/sbi.h"
 
 #include "memory/memory.h"
 #include "memory/mmu/mmu.h"
@@ -510,7 +511,7 @@ static void cpu_execute(rv32_cpu_t* cpu, instruction_t* instruction)
 					switch(instruction->immediate)
 					{
 						case IMM_ECALL:
-							fprintf(stderr, "ECALL: a7(sbi ext id) = %d, a6(sbi funct id) = %d\n", cpu->regs.a7, cpu->regs.a6);
+							sbi_call(cpu, cpu->regs.a7, cpu->regs.a6);
 							break;
 						case IMM_EBREAK:
 							// EBREAK : on debug, give back hand to debugger ; without debug, end simulation
diff --git a/src/devices/sbi/sbi.c b/src/devices/sbi/sbi.c
new file mode 100644
index 0000000..9382022
--- /dev/null
+++ b/src/devices/sbi/sbi.c
@@ -0,0 +1,27 @@
+#include "sbi.h"
+
+#include <stdio.h>
+
+void sbi_call(rv32_cpu_t* cpu, uint32_t extension_id, uint32_t func_id)
+{
+	switch(extension_id)
+	{
+		case SBI_EXTENSION_LEGACY_CONSOLE_PUTCHAR:
+		{
+            printf("%c", cpu->regs.a0);
+            cpu->regs.a0 = 0;
+            break;
+		}
+        case SBI_EXTENSION_LEGACY_SHUTDOWN:
+        {
+			printf("sbi_call: shutdown, goodbye !\n");
+            cpu->sim_ticks_left = 1;
+            break;
+        }
+		default:
+		{
+			fprintf(stderr, "sbi_call: unknown extension id 0x%x\n", extension_id);
+            break;
+		}
+	}
+}
diff --git a/src/devices/sbi/sbi.h b/src/devices/sbi/sbi.h
new file mode 100644
index 0000000..ce4f182
--- /dev/null
+++ b/src/devices/sbi/sbi.h
@@ -0,0 +1,11 @@
+#ifndef SBI_H
+#define SBI_H
+
+#include "cpu/rv32cpu.h"
+
+#define SBI_EXTENSION_LEGACY_CONSOLE_PUTCHAR 0x1
+#define SBI_EXTENSION_LEGACY_SHUTDOWN 0x8
+
+void sbi_call(rv32_cpu_t* cpu, uint32_t extension_id, uint32_t func_id);
+
+#endif
diff --git a/src/main.c b/src/main.c
index 784f40b..1aa8008 100644
--- a/src/main.c
+++ b/src/main.c
@@ -52,7 +52,7 @@ int main(int argc, char** argv)
 			pthread_mutex_unlock(&cpu0_mutex);
 		}
 
-        fprintf(stderr, "Simulation ended in a non-debug environment\n");
+        fprintf(stderr, "Simulation ended (in a non-debug environment)\n");
         return cpu0->regs.a0;
 	}