target/arm: Move vfp_expand_imm() to translate.[ch]

We want to use vfp_expand_imm() in the AArch32 VFP decode;
move it from the a64-only header/source file to the
AArch32 one (which is always compiled even for AArch64).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190613163917.28589-2-peter.maydell@linaro.org

1 files changed, 33 insertions, 0 deletions

diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
index 709fc65374..a66084f6e3 100644
--- a/target/arm/translate-vfp.inc.c
+++ b/target/arm/translate-vfp.inc.c
@@ -31,6 +31,39 @@
 #include "decode-vfp-uncond.inc.c"
 
 /*
+ * The imm8 encodes the sign bit, enough bits to represent an exponent in
+ * the range 01....1xx to 10....0xx, and the most significant 4 bits of
+ * the mantissa; see VFPExpandImm() in the v8 ARM ARM.
+ */
+uint64_t vfp_expand_imm(int size, uint8_t imm8)
+{
+    uint64_t imm;
+
+    switch (size) {
+    case MO_64:
+        imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
+            (extract32(imm8, 6, 1) ? 0x3fc0 : 0x4000) |
+            extract32(imm8, 0, 6);
+        imm <<= 48;
+        break;
+    case MO_32:
+        imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
+            (extract32(imm8, 6, 1) ? 0x3e00 : 0x4000) |
+            (extract32(imm8, 0, 6) << 3);
+        imm <<= 16;
+        break;
+    case MO_16:
+        imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
+            (extract32(imm8, 6, 1) ? 0x3000 : 0x4000) |
+            (extract32(imm8, 0, 6) << 6);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+    return imm;
+}
+
+/*
  * Return the offset of a 16-bit half of the specified VFP single-precision
  * register. If top is true, returns the top 16 bits; otherwise the bottom
  * 16 bits.