[tests] add basic OS interface operation symbols

A working sbrk is implemented.

Signed-off-by: Avimitin <[email protected]>

flake.nix

@@ -42,6 +42,7 @@
             go
             buddy-mlir
             rvv-codegen
+            rv32-gnu-toolchain
           ];
 
           emulatorDeps = with pkgs; [

overlay.nix

@@ -79,6 +79,7 @@ in
   buddy-mlir = final.callPackage ./nix/buddy-mlir.nix { };
   rvv-codegen = final.callPackage ./nix/rvv-codegen.nix { };
   rvv-testcase = final.callPackage ./nix/rvv-testcase-unwrapped.nix { };
+  rv32-gnu-toolchain = final.callPackage ./nix/riscv-gnu-toolchain.nix { };
 
   inherit rv32-clang my-cc-wrapper;
 }

tests/intrinsic/main.S

@@ -1,4 +1,5 @@
     .globl start
+    .globl heap_end
 start:
     li a0, 0x2200 # MSTATUS_VS & (MSTATUS_VS >> 1)
     csrs mstatus, a0
@@ -14,3 +15,8 @@ stack_start:
     .zero 0x10000
 
 stack_end:
+
+heap_start:
+    .zero 0x100000
+
+heap_end:

tests/intrinsic/sys.c

@@ -0,0 +1,34 @@
+extern char* heap_end;
+char *heap_ptr;
+
+char *_sbrk(int nbytes) {
+  char *base;
+
+  if (!heap_ptr)
+    heap_ptr = (char *)&heap_end;
+  base = heap_ptr;
+  heap_ptr += nbytes;
+
+  return base;
+}
+
+void _exit(int code) {
+  __asm__("csrwi 0x7cc, 0");
+  __builtin_unreachable();
+}
+
+int _close(int file) {
+  return -1;
+}
+
+int _lseek(int file, int ptr, int dir) {
+  return -1;
+}
+
+int _read(int file, char* ptr, int len) {
+  return -1;
+}
+
+int _write(int file, char* ptr, int len) {
+  return -1;
+}