[Qemu-ppc] [PATCH v1 04/10] target-ppc: Implement darn instruction

[Nikunj A Dadhania]

From: Ravi Bangoria <address@hidden>

darn: Deliver A Random Number

For both CRN and RRN, returning 64-bit random number.

Signed-off-by: Ravi Bangoria <address@hidden>
[ use /dev/random to get the number ]
Signed-off-by: Nikunj A Dadhania <address@hidden>
---
 target-ppc/helper.h     |  2 ++
 target-ppc/int_helper.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 target-ppc/translate.c  | 18 +++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/target-ppc/helper.h b/target-ppc/helper.h
index 8eada2f..0e55d48 100644
--- a/target-ppc/helper.h
+++ b/target-ppc/helper.h
@@ -50,6 +50,8 @@ DEF_HELPER_FLAGS_1(cnttzd, TCG_CALL_NO_RWG_SE, tl, tl)
 DEF_HELPER_FLAGS_1(popcntd, TCG_CALL_NO_RWG_SE, tl, tl)
 DEF_HELPER_FLAGS_2(bpermd, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 DEF_HELPER_3(srad, tl, env, tl, tl)
+DEF_HELPER_0(darn32, tl)
+DEF_HELPER_0(darn64, tl)
 #endif
 
 DEF_HELPER_FLAGS_1(cntlsw32, TCG_CALL_NO_RWG_SE, i32, i32)
diff --git a/target-ppc/int_helper.c b/target-ppc/int_helper.c
index 552b2e0..5b70054 100644
--- a/target-ppc/int_helper.c
+++ b/target-ppc/int_helper.c
@@ -182,6 +182,57 @@ target_ulong helper_cnttzd(target_ulong t)
 {
     return ctz64(t);
 }
+
+#define FILE_DEV_RANDOM "/dev/random"
+
+static bool get_random(char *s, size_t size)
+{
+    int fd;
+    size_t bytes_read;
+
+    fd = open(FILE_DEV_RANDOM, O_RDONLY);
+    if (fd < 0) {
+        return false;
+    }
+
+    while (size > 0) {
+        bytes_read = read(fd, s, size);
+        if (bytes_read <= 0) {
+            close(fd);
+            return false;
+        }
+        size -= bytes_read;
+        s += bytes_read;
+    }
+    close(fd);
+    return true;
+}
+
+target_ulong helper_darn32(void)
+{
+    char s[4];
+    if (!get_random(s, 4)) {
+        return 0;
+    }
+
+    return *((uint32_t *)s);
+}
+
+target_ulong helper_darn64(void)
+{
+    char s[8];
+    uint64_t  val;
+
+    do {
+        if (!get_random(s, 8)) {
+            return -1;
+        }
+        val = *((uint64_t *)s);
+    } while (val == UINT64_MAX);
+
+    return val;
+}
+
 #endif
 
 #if defined(TARGET_PPC64)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index c7bbe28..67eac9f 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -526,6 +526,8 @@ EXTRACT_HELPER(FPW, 16, 1);
 
 /* addpcis */
 EXTRACT_HELPER_DXFORM(DX, 10, 6, 6, 5, 16, 1, 1, 0, 0)
+/* darn */
+EXTRACT_HELPER(L, 16, 2);
 
 /***                            Jump target decoding                       ***/
 /* Immediate address */
@@ -1893,6 +1895,21 @@ static void gen_cnttzd(DisasContext *ctx)
         gen_set_Rc0(ctx, cpu_gpr[rA(ctx->opcode)]);
     }
 }
+
+/* darn */
+static void gen_darn(DisasContext *ctx)
+{
+    int l = L(ctx->opcode);
+
+    if (l == 0) {
+        gen_helper_darn32(cpu_gpr[rD(ctx->opcode)]);
+    } else if (l <= 2) {
+        /* Return 64-bit random for both CRN and RRN */
+        gen_helper_darn64(cpu_gpr[rD(ctx->opcode)]);
+    } else {
+        tcg_gen_movi_i64(cpu_gpr[rD(ctx->opcode)], -1);
+    }
+}
 #endif
 
 /***                             Integer rotate                            ***/
@@ -6219,6 +6236,7 @@ GEN_HANDLER_E(prtyw, 0x1F, 0x1A, 0x04, 0x0000F801, 
PPC_NONE, PPC2_ISA205),
 GEN_HANDLER(popcntd, 0x1F, 0x1A, 0x0F, 0x0000F801, PPC_POPCNTWD),
 GEN_HANDLER(cntlzd, 0x1F, 0x1A, 0x01, 0x00000000, PPC_64B),
 GEN_HANDLER_E(cnttzd, 0x1F, 0x1A, 0x11, 0x00000000, PPC_NONE, PPC2_ISA300),
+GEN_HANDLER_E(darn, 0x1F, 0x13, 0x17, 0x001CF801, PPC_NONE, PPC2_ISA300),
 GEN_HANDLER_E(prtyd, 0x1F, 0x1A, 0x05, 0x0000F801, PPC_NONE, PPC2_ISA205),
 GEN_HANDLER_E(bpermd, 0x1F, 0x1C, 0x07, 0x00000001, PPC_NONE, 
PPC2_PERM_ISA206),
 #endif
-- 
2.7.4