target/s390x: Implement SRSTU

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

1 files changed, 41 insertions, 0 deletions

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 2e3941f0c6..1926db721c 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -576,6 +576,47 @@ void HELPER(srst)(CPUS390XState *env, uint32_t r1, uint32_t r2)
     set_address(env, r2, str + len);
 }
 
+void HELPER(srstu)(CPUS390XState *env, uint32_t r1, uint32_t r2)
+{
+    uintptr_t ra = GETPC();
+    uint32_t len;
+    uint16_t v, c = env->regs[0];
+    uint64_t end, str, adj_end;
+
+    /* Bits 32-47 of R0 must be zero.  */
+    if (env->regs[0] & 0xffff0000u) {
+        cpu_restore_state(ENV_GET_CPU(env), ra);
+        program_interrupt(env, PGM_SPECIFICATION, 6);
+    }
+
+    str = get_address(env, r2);
+    end = get_address(env, r1);
+
+    /* If the LSB of the two addresses differ, use one extra byte.  */
+    adj_end = end + ((str ^ end) & 1);
+
+    /* Lest we fail to service interrupts in a timely manner, limit the
+       amount of work we're willing to do.  For now, let's cap at 8k.  */
+    for (len = 0; len < 0x2000; len += 2) {
+        if (str + len == adj_end) {
+            /* End of input found.  */
+            env->cc_op = 2;
+            return;
+        }
+        v = cpu_lduw_data_ra(env, str + len, ra);
+        if (v == c) {
+            /* Character found.  Set R1 to the location; R2 is unmodified.  */
+            env->cc_op = 1;
+            set_address(env, r1, str + len);
+            return;
+        }
+    }
+
+    /* CPU-determined bytes processed.  Advance R2 to next byte to process.  */
+    env->cc_op = 3;
+    set_address(env, r2, str + len);
+}
+
 /* unsigned string compare (c is string terminator) */
 uint64_t HELPER(clst)(CPUS390XState *env, uint64_t c, uint64_t s1, uint64_t s2)
 {