target/s390x: implement PACK ASCII

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <20170531220129.27724-24-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 35 insertions, 0 deletions

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 581f10760b..4cf96c8485 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -914,6 +914,41 @@ void HELPER(pack)(CPUS390XState *env, uint32_t len, uint64_t dest, uint64_t src)
     }
 }
 
+void HELPER(pka)(CPUS390XState *env, uint64_t dest, uint64_t src,
+                 uint32_t srclen)
+{
+    uintptr_t ra = GETPC();
+    int i;
+    /* The destination operand is always 16 bytes long.  */
+    const int destlen = 16;
+
+    /* The operands are processed from right to left.  */
+    src += srclen - 1;
+    dest += destlen - 1;
+
+    for (i = 0; i < destlen; i++) {
+        uint8_t b = 0;
+
+        /* Start with a positive sign */
+        if (i == 0) {
+            b = 0xc;
+        } else if (srclen > 1) {
+            b = cpu_ldub_data_ra(env, src, ra) & 0x0f;
+            src--;
+            srclen--;
+        }
+
+        if (srclen > 1) {
+            b |= cpu_ldub_data_ra(env, src, ra) << 4;
+            src--;
+            srclen--;
+        }
+
+        cpu_stb_data_ra(env, dest, b, ra);
+        dest--;
+    }
+}
+
 void HELPER(unpk)(CPUS390XState *env, uint32_t len, uint64_t dest,
                   uint64_t src)
 {