Fix: test_bitfield: extend coverage: 0-len signed write/read

By convention, a 0-len bitfield write is a no-op, and a 0-len read
sets the value of the output to 0.

So we can "encode" the value 0 over a length of 0 bit. Cover this
in the test-cases for signed types. It is already covered for the
unsigned test-cases.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ib6038b98167ef2cfa8c504d7ac29498e71827b38
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1341
Tested-by: jenkins

diff --git a/tests/lib/test_bitfield.c b/tests/lib/test_bitfield.c
index bc61e11895f5af8c482c979768e55188643b63de..2dc657194f60d498f7cf72567a3f8e126fa4f3b2 100644 (file)
--- a/tests/lib/test_bitfield.c
+++ b/tests/lib/test_bitfield.c
@@ -387,7 +387,9 @@ void run_test_signed_write(int src_i, long long src_ll)
        long long readval;
        unsigned int s, l;
 
        long long readval;
        unsigned int s, l;
 

-       if (src_i & 0x80000000U)
+       if (!src_i)
+               nrbits_i = 0;                   /* The number of bits needed to represent 0 is 0. */
+       else if (src_i & 0x80000000U)

                nrbits_i = fls_u32(~src_i) + 1; /* Find least significant bit conveying sign */
        else
                nrbits_i = fls_u32(src_i) + 1;  /* Keep sign at 0 */
                nrbits_i = fls_u32(~src_i) + 1; /* Find least significant bit conveying sign */
        else
                nrbits_i = fls_u32(src_i) + 1;  /* Keep sign at 0 */


@@ -438,7 +440,9 @@ void run_test_signed_write(int src_i, long long src_ll)
        }
        pass(SIGNED_INT_WRITE_TEST_DESC_FMT_STR, src_i);
 
        }
        pass(SIGNED_INT_WRITE_TEST_DESC_FMT_STR, src_i);
 

-       if (src_ll & 0x8000000000000000ULL)
+       if (!src_ll)
+               nrbits_ll = 0;                          /* The number of bits needed to represent 0 is 0. */
+       else if (src_ll & 0x8000000000000000ULL)

                nrbits_ll = fls_u64(~src_ll) + 1;       /* Find least significant bit conveying sign */
        else
                nrbits_ll = fls_u64(src_ll) + 1;        /* Keep sign at 0 */
                nrbits_ll = fls_u64(~src_ll) + 1;       /* Find least significant bit conveying sign */
        else
                nrbits_ll = fls_u64(src_ll) + 1;        /* Keep sign at 0 */


@@ -503,7 +507,9 @@ void run_test_signed_read(int src_i, long long src_ll)
        long long readval_ll;
        unsigned int s, l;
 
        long long readval_ll;
        unsigned int s, l;
 

-       if (src_i & 0x80000000U)
+       if (!src_i)
+               nrbits_i = 0;                   /* The number of bits needed to represent 0 is 0. */
+       else if (src_i & 0x80000000U)

                nrbits_i = fls_u32(~src_i) + 1; /* Find least significant bit conveying sign */
        else
                nrbits_i = fls_u32(src_i) + 1;  /* Keep sign at 0 */
                nrbits_i = fls_u32(~src_i) + 1; /* Find least significant bit conveying sign */
        else
                nrbits_i = fls_u32(src_i) + 1;  /* Keep sign at 0 */


@@ -554,6 +560,8 @@ void run_test_signed_read(int src_i, long long src_ll)
        }
        pass(SIGNED_INT_READ_TEST_DESC_FMT_STR, src_i);
 
        }
        pass(SIGNED_INT_READ_TEST_DESC_FMT_STR, src_i);
 

+       if (!src_ll)
+               nrbits_ll = 0;                          /* The number of bits needed to represent 0 is 0. */

        if (src_ll & 0x8000000000000000ULL)
                nrbits_ll = fls_u64(~src_ll) + 1;       /* Find least significant bit conveying sign */
        else
        if (src_ll & 0x8000000000000000ULL)
                nrbits_ll = fls_u64(~src_ll) + 1;       /* Find least significant bit conveying sign */
        else