commit 0ec92ecb47a3a0093deb0f285e0d05d011cf06d9
from: Benjamin Stürz <benni@stuerz.xyz>
date: Tue Feb 20 18:51:20 2024 UTC

fix bne and make ebreak useful

commit - a67f2fcdcd5d5cc91b1aac7a4c600482f600a732
commit + 0ec92ecb47a3a0093deb0f285e0d05d011cf06d9
blob - c1b64dea367cf49f7f9f16f859eb4ff99407573e
blob + 56c7fd9329171d775185b57763c510b8323df1a0
--- Makefile
+++ Makefile
@@ -10,7 +10,7 @@ CROSS	= ./tools/bin/${TARGET}
 CFLAGS	= -std=c2x -fPIC -O0 -g
 LDFLAGS	= -pie -static -lpthread
 OBJ	= rvemu.o ecall.o cpu.o exec.o
-PROGS	= test.elf hello.elf
+PROGS	= test.elf test2.elf hello.elf
 
 all: rvemu ${PROGS}
 
blob - 6d0a65ab8870c771e0c20ac41212797db275fd74
blob + a705236c9bc04ebc05144792b2c9cc7cded54f0a
--- cpu.c
+++ cpu.c
@@ -88,6 +88,7 @@ void cpu_exec (u32 instr)
 		case 0b001:
 			name = "bne";
 			c = a != b;
+			break;
 		case 0b100:
 			name = "blt";
 			c = (i64)a < (i64)b;
@@ -367,17 +368,22 @@ void cpu_exec (u32 instr)
 		eprintf ("%08llx: efence\n", pc - 4);
 		break;
 	case 0b1110011: // ecall/ebreak
-		log (
-			"ecall a0=%llu, a1=%llu, a2=%llu, a3=%llu, a4=%llu, a5=%llu, a7=%llu",
-			cpu_get (10),
-			cpu_get (11),
-			cpu_get (12),
-			cpu_get (13),
-			cpu_get (14),
-			cpu_get (15),
-			cpu_get (17)
-		);
-		ecall ();
+		if ((instr >> 20) & 1) {
+			eprintf ("%08llx: ebreak\n", pc - 4);
+			__asm __volatile__ ("int $3");
+		} else {
+			log (
+				"ecall a0=%llu, a1=%llu, a2=%llu, a3=%llu, a4=%llu, a5=%llu, a7=%llu",
+				cpu_get (10),
+				cpu_get (11),
+				cpu_get (12),
+				cpu_get (13),
+				cpu_get (14),
+				cpu_get (15),
+				cpu_get (17)
+			);
+			ecall ();
+		}
 		break;
 	default:
 	ud:
blob - 4cb95aa505e1a5d33bd0d37ed1fb0f4f115b2b67
blob + f1fa870f78600a53528abcc226d280124e392286
--- rvemu.h
+++ rvemu.h
@@ -4,7 +4,7 @@
 #include <stdio.h>
 #include <err.h>
 
-#define DEBUG 1
+#define DEBUG 0
 
 #if DEBUG
 # define eprintf(...) fprintf (stderr, __VA_ARGS__)
blob - 70f3e50ce557283d9025cf3c7e821c05c080395b
blob + 7ae62507ac23f2c3e6716f44bfdb437b02dbc5f6
--- test.c
+++ test.c
@@ -3,14 +3,14 @@
 
 const char *volatile str = "Hello World!\n";
 
-size_t my_strlen (const char *s)
+__attribute__((always_inline))
+inline static void ebreak (void)
 {
-	size_t i;
-	for (i = 0; s[i] != '\0'; ++i);
-	return i;
+	__asm __volatile__ ("ebreak");
 }
 
 int main (void) {
-	const size_t len = my_strlen (str);
-	return len;
+	const size_t len = strlen (str);
+	write (1, str, len);
+	return 0;
 }