riscv

commit 78f5bde3560fc41e88ceee3c4e46d9fa8cb3d3e1
parent 85d3efcca64bf41f52b5763af6ae11b88afc8235
Author: Brian Swetland <swetland@frotz.net>
Date:   Fri, 18 Oct 2019 21:39:26 -0700

rvsim: move memory to 0x80000000

- test suite is setup this way
- stub in ior() iow() for accesses below 0x80000000

Diffstat:
M
rvsim.c
 | 
26
+++++++++++++++++++++-----
M
simple.ld
 | 
4
++--

2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/rvsim.c b/rvsim.c
@@ -34,14 +34,29 @@ int load_image(const char* fn, uint8_t* ptr, size_t sz) {
 	return 0;
 }
 
+uint32_t ior32(uint32_t addr) {
+	return 0xffffffff;
+}
+
+void iow32(uint32_t addr, uint32_t val) {
+}
+
 uint32_t rd32(uint32_t addr) {
-	addr &= (sizeof(memory) - 1);
-	return ((uint32_t*) memory)[addr >> 2];
+	if (addr < 0x80000000) {
+		return ior32(addr);
+	} else {
+		addr &= (sizeof(memory) - 1);
+		return ((uint32_t*) memory)[addr >> 2];
+	}
 }
 
 void wr32(uint32_t addr, uint32_t val) {
-	addr &= (sizeof(memory) - 1);
-	((uint32_t*) memory)[addr >> 2] = val;
+	if (addr < 0x80000000) {
+		iow32(addr, val);
+	} else {
+		addr &= (sizeof(memory) - 1);
+		((uint32_t*) memory)[addr >> 2] = val;
+	}
 }
 
 typedef struct {
@@ -53,7 +68,7 @@ void rvsim(rvstate* s) {
 	char dis[128];
 	uint32_t pc, ins;
 	pc = s->pc;
-	while (pc < 64) {
+	while (pc < 0x80000100) {
 		ins = rd32(pc);
 		rvdis(pc, ins, dis);
 		printf("%08x: %08x %s\n", pc, ins, dis);
@@ -66,6 +81,7 @@ int main(int argc, char** argv) {
 	rvstate s;
 	if (load_image("out/hello.bin", memory, sizeof(memory)) < 0) return -1;
 	memset(&s, 0, sizeof(s));
+	s.pc = 0x80000000;
 	rvsim(&s);
 	return 0;
 }
diff --git a/simple.ld b/simple.ld
@@ -1,11 +1,11 @@
 
 MEMORY {
-	mem : ORIGIN = 0x00000000, LENGTH = 0x00020000
+	mem : ORIGIN = 0x80000000, LENGTH = 0x00010000
 }
 
 SECTIONS {
 	.memory : {
-		. = 0x000000;
+		. = 0x00000000;
 		start*(.text);
 		*(.text);
 		*(*);