PACK fails on the test from the Principles of Operation: F1F2F3F4
becomes 0000234C instead of 0001234C due to an off-by-one error.
Furthermore, it overwrites one extra byte to the left of F1.
If len_dest is 0, then we only want to flip the 1st byte and never loop
over the rest. Therefore, the loop condition should be > and not >=.
If len_src is 1, then we should flip the 1st byte and pack the 2nd.
Since len_src is already decremented before the loop, the first
condition should be >=, and not >.
Likewise for len_src == 2 and the second condition.
Signed-off-by: Pavel Zbitskiy <pavel.zbits...@gmail.com>
---
target/s390x/mem_helper.c | 6 +++---
tests/tcg/s390x/Makefile.target | 1 +
tests/tcg/s390x/pack.c | 21 +++++++++++++++++++++
3 files changed, 25 insertions(+), 3 deletions(-)
create mode 100644 tests/tcg/s390x/pack.c
diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 704d0193b5..bacae4f503 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -1019,15 +1019,15 @@ void HELPER(pack)(CPUS390XState *env, uint32_t len,
uint64_t dest, uint64_t src)
len_src--;
/* now pack every value */
- while (len_dest >= 0) {
+ while (len_dest > 0) {
b = 0;
- if (len_src > 0) {
+ if (len_src >= 0) {
b = cpu_ldub_data_ra(env, src, ra) & 0x0f;
src--;
len_src--;
}
- if (len_src > 0) {
+ if (len_src >= 0) {
b |= cpu_ldub_data_ra(env, src, ra) << 4;
src--;
len_src--;
diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
index 7de4376f52..151dc075aa 100644
--- a/tests/tcg/s390x/Makefile.target
+++ b/tests/tcg/s390x/Makefile.target
@@ -5,3 +5,4 @@ TESTS+=csst
TESTS+=ipm
TESTS+=exrl-trt
TESTS+=exrl-trtr
+TESTS+=pack
diff --git a/tests/tcg/s390x/pack.c b/tests/tcg/s390x/pack.c
new file mode 100644
index 0000000000..4be36f29a7
--- /dev/null
+++ b/tests/tcg/s390x/pack.c
@@ -0,0 +1,21 @@
+#include <unistd.h>
+
+int main(void)
+{
+ char data[] = {0xaa, 0xaa, 0xf1, 0xf2, 0xf3, 0xc4, 0xaa, 0xaa};
+ char exp[] = {0xaa, 0xaa, 0x00, 0x01, 0x23, 0x4c, 0xaa, 0xaa};
+ int i;
+
+ asm volatile(
+ " pack 2(4,%[data]),2(4,%[data])\n"
+ :
+ : [data] "r" (&data[0])
+ : "memory");
+ for (i = 0; i < 8; i++) {
+ if (data[i] != exp[i]) {
+ write(1, "bad data\n", 9);
+ return 1;
+ }
+ }
+ return 0;
+}
--
2.18.0
