Added basic SBI support

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

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

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;
+		}
+	}
+}

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

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;
 	}