1 files changed, 104 insertions, 0 deletions
diff --git a/tests/tst-overlap.c b/tests/tst-overlap.c
new file mode 100644
index 0000000..9de9286
--- /dev/null
+++ b/tests/tst-overlap.c
@@ -0,0 +1,104 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+
+#include <libmcpu.h>
+
+
+static int failures = 0;
+
+#define CHECK(cond,msg) \
+  do { \
+    if( !(cond) ) \
+    { \
+      fprintf( stderr, "FAIL: %s\n", (msg) ); \
+      ++failures; \
+    } \
+  } while( 0 )
+
+
+int
+main( void )
+{
+  __mpu_UNIT_t *r64;
+  __mpu_UNIT_t *r32_0;
+  __mpu_UNIT_t *r32_4;
+  __mpu_UNIT_t *r16_2;
+  __mpu_UNIT_t *r8_3;
+  unsigned int i;
+
+  __cpu_init();
+
+  r64   = __cpu_reg_ptr( 64, 0 );
+  r32_0 = __cpu_reg_ptr( 32, 0 );
+  r32_4 = __cpu_reg_ptr( 32, 4 );
+  r16_2 = __cpu_reg_ptr( 16, 2 );
+  r8_3  = __cpu_reg_ptr(  8, 3 );
+
+  CHECK( r64   != 0, "r64@0 pointer" );
+  CHECK( r32_0 != 0, "r32@0 pointer" );
+  CHECK( r32_4 != 0, "r32@4 pointer" );
+  CHECK( r16_2 != 0, "r16@2 pointer" );
+  CHECK( r8_3  != 0, "r8@3 pointer" );
+
+  CHECK( r64 == r32_0, "r64@0 and r32@0 start at same byte" );
+  CHECK( r32_4 == r64 + 4, "r32@4 overlaps upper four bytes of r64@0" );
+  CHECK( r16_2 == r64 + 2, "r16@2 overlaps bytes 2..3 of r64@0" );
+  CHECK( r8_3 == r64 + 3, "r8@3 overlaps byte 3 of r64@0" );
+
+  for( i = 0; i < 8; ++i ) r64[i] = (__mpu_UNIT_t)( 0x10 + i );
+
+  CHECK( r32_0[0] == 0x10 && r32_0[1] == 0x11 &&
+         r32_0[2] == 0x12 && r32_0[3] == 0x13,
+         "r32@0 sees bytes written through r64@0" );
+
+  CHECK( r32_4[0] == 0x14 && r32_4[1] == 0x15 &&
+         r32_4[2] == 0x16 && r32_4[3] == 0x17,
+         "r32@4 sees bytes written through r64@0" );
+
+  CHECK( r16_2[0] == 0x12 && r16_2[1] == 0x13,
+         "r16@2 sees bytes written through r64@0" );
+
+  *r8_3 = 0xa5;
+  CHECK( r64[3] == 0xa5,
+         "write through r8@3 changes r64@0 storage" );
+  CHECK( r32_0[3] == 0xa5,
+         "write through r8@3 changes r32@0 storage" );
+  CHECK( r16_2[1] == 0xa5,
+         "write through r8@3 changes r16@2 storage" );
+
+  /* Check the same property at a non-zero naturally aligned address. */
+  {
+    __mpu_UNIT_t *r128 = __cpu_reg_ptr( 128, 0x00100 );
+    __mpu_UNIT_t *r32  = __cpu_reg_ptr(  32, 0x0010c );
+    __mpu_UNIT_t *r8   = __cpu_reg_ptr(   8, 0x0010f );
+
+    CHECK( r128 != 0 && r32 != 0 && r8 != 0,
+           "overlap pointers at 0x00100" );
+    CHECK( r32 == r128 + 12,
+           "r32@0x0010c inside r128@0x00100" );
+    CHECK( r8 == r128 + 15,
+           "r8@0x0010f inside r128@0x00100" );
+
+    r128[15] = 0x5a;
+    CHECK( *r8 == 0x5a,
+           "r8 view sees r128 storage" );
+
+    r32[3] = 0xc3;
+    CHECK( r128[15] == 0xc3,
+           "r32 view changes r128 storage" );
+  }
+
+  if( failures != 0 )
+  {
+    fprintf( stderr, "libcpu overlap regression: %d failure(s)\n", failures );
+    return( 1 );
+  }
+
+  printf( "libcpu 0.0.3 overlapping register views regression: PASS\n" );
+  printf( "overlap is byte-storage aliasing and is endian independent\n" );
+
+  return( 0 );
+}