From 8b98dbd409379e9efa6a58da4b8bf3d7d252f1a8 Mon Sep 17 00:00:00 2001
From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 30 Oct 2018 01:14:06 +0000
Subject: [PATCH] add sv_proc_t f32 conversions when elwidth=16bit

---
 riscv/decode.h            |  4 ++++
 riscv/sv_insn_redirect.cc | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/riscv/decode.h b/riscv/decode.h
index 6e11c46..bc0bd79 100644
--- a/riscv/decode.h
+++ b/riscv/decode.h
@@ -234,13 +234,17 @@ private:
 #define invalid_pc(pc) ((pc) & 1)
 
 /* Convenience wrappers to simplify softfloat code sequences */
+#define unboxF16(r) (isBoxedF16(r) ? (uint16_t)r.v[0] : defaultNaNF16UI)
+#define isBoxedF16(r) (isBoxedF32(r) && ((uint16_t)((r.v[0] >> 16) + 1) == 0))
 #define isBoxedF32(r) (isBoxedF64(r) && ((uint32_t)((r.v[0] >> 32) + 1) == 0))
 #define unboxF32(r) (isBoxedF32(r) ? (uint32_t)r.v[0] : defaultNaNF32UI)
 #define isBoxedF64(r) ((r.v[1] + 1) == 0)
 #define unboxF64(r) (isBoxedF64(r) ? r.v[0] : defaultNaNF64UI)
 typedef float128_t freg_t;
+inline float16_t f16(uint16_t v) { return { v }; }
 inline float32_t f32(uint32_t v) { return { v }; }
 inline float64_t f64(uint64_t v) { return { v }; }
+inline float16_t f16(freg_t r) { return f16(unboxF16(r)); }
 inline float32_t f32(freg_t r) { return f32(unboxF32(r)); }
 inline float64_t f64(freg_t r) { return f64(unboxF64(r)); }
 inline float128_t f128(freg_t r) { return r; }
diff --git a/riscv/sv_insn_redirect.cc b/riscv/sv_insn_redirect.cc
index a6dba3a..23faeb9 100644
--- a/riscv/sv_insn_redirect.cc
+++ b/riscv/sv_insn_redirect.cc
@@ -399,12 +399,32 @@ sv_reg_t sv_proc_t::sv_reg_uint32(sv_reg_t const& v)
 
 sv_float32_t (sv_proc_t::f32)(sv_freg_t x)
 {
+    switch (x.get_elwidth())
+    {
+        // 8-bit
+        case 1: throw trap_illegal_instruction(0); // XXX for now
+        // 16-bit data, up-convert to f32
+        case 2:
+            return f16_to_f32(f16(x.to_uint32()));
+        // 0 and 3 are 32-bit
+        default: break;
+    }
     return ::f32(x);
 }
 
 sv_float32_t (sv_proc_t::f32)(sv_reg_t const& v)
 {
     uint64_t x = v;
+    switch (v.get_elwidth())
+    {
+        // 8-bit
+        case 1: throw trap_illegal_instruction(0); // XXX for now
+        // 16-bit data, up-convert to f32
+        case 2:
+            return f16_to_f32(f16(x));
+        // 0 and 3 are 32-bit
+        default: break;
+    }
     return ::f32(x);
 }
 
-- 
2.30.2