target/s390x: implement UNPACK ASCII

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <20170531220129.27724-26-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 51 insertions, 0 deletions

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 218f1ab1fd..b87e41764f 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -1008,6 +1008,57 @@ void HELPER(unpk)(CPUS390XState *env, uint32_t len, uint64_t dest,
     }
 }
 
+uint32_t HELPER(unpka)(CPUS390XState *env, uint64_t dest, uint32_t destlen,
+                       uint64_t src)
+{
+    uintptr_t ra = GETPC();
+    int i;
+    uint32_t cc;
+    uint8_t b;
+    /* The source operand is always 16 bytes long.  */
+    const int srclen = 16;
+
+    /* The operands are processed from right to left.  */
+    src += srclen - 1;
+    dest += destlen - 1;
+
+    /* Check for the sign.  */
+    b = cpu_ldub_data_ra(env, src, ra);
+    src--;
+    switch (b & 0xf) {
+    case 0xa:
+    case 0xc:
+    case 0xe ... 0xf:
+        cc = 0;  /* plus */
+        break;
+    case 0xb:
+    case 0xd:
+        cc = 1;  /* minus */
+        break;
+    default:
+    case 0x0 ... 0x9:
+        cc = 3;  /* invalid */
+        break;
+    }
+
+    /* Now pad every nibble with 0x30, advancing one nibble at a time. */
+    for (i = 0; i < destlen; i++) {
+        if (i == 31) {
+            /* If length is 32 bytes, the leftmost byte is 0. */
+            b = 0;
+        } else if (i % 2) {
+            b = cpu_ldub_data_ra(env, src, ra);
+            src--;
+        } else {
+            b >>= 4;
+        }
+        cpu_stb_data_ra(env, dest, 0x30 + (b & 0xf), ra);
+        dest--;
+    }
+
+    return cc;
+}
+
 static uint32_t do_helper_tr(CPUS390XState *env, uint32_t len, uint64_t array,
                              uint64_t trans, uintptr_t ra)
 {