CRIS: Convert lz (leading zeros) to TCG.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4309 c046a42c-6fe2-441c-8c8c-71466251a162

diff --git a/target-cris/translate.c b/target-cris/translate.c
index 72e5e3c06aa6adcdd0fca3e020c28d0511862c19..04632f57ec751ebbcf443331ffd36179e8d7de8b 100644 (file)
--- a/target-cris/translate.c
+++ b/target-cris/translate.c
@@ -307,6 +307,74 @@ static void t_gen_mulu(TCGv d, TCGv d2, TCGv a, TCGv b)
        tcg_gen_discard_i64(t1);
 }
 
+/* 32bit branch-free binary search for counting leading zeros.  */
+static void t_gen_lz_i32(TCGv d, TCGv x)
+{
+       TCGv y, m, n;
+
+       y = tcg_temp_new(TCG_TYPE_I32);
+       m = tcg_temp_new(TCG_TYPE_I32);
+       n = tcg_temp_new(TCG_TYPE_I32);
+
+       /* y = -(x >> 16)  */
+       tcg_gen_shri_i32(y, x, 16);
+       tcg_gen_sub_i32(y, tcg_const_i32(0), y);
+
+       /* m = (y >> 16) & 16  */
+       tcg_gen_sari_i32(m, y, 16);
+       tcg_gen_andi_i32(m, m, 16);
+
+       /* n = 16 - m  */
+       tcg_gen_sub_i32(n, tcg_const_i32(16), m);
+       /* x = x >> m  */
+       tcg_gen_shr_i32(x, x, m);
+
+       /* y = x - 0x100  */
+       tcg_gen_subi_i32(y, x, 0x100);
+       /* m = (y >> 16) & 8  */
+       tcg_gen_sari_i32(m, y, 16);
+       tcg_gen_andi_i32(m, m, 8);
+       /* n = n + m  */
+       tcg_gen_add_i32(n, n, m);
+       /* x = x << m  */
+       tcg_gen_shl_i32(x, x, m);
+
+       /* y = x - 0x1000  */
+       tcg_gen_subi_i32(y, x, 0x1000);
+       /* m = (y >> 16) & 4  */
+       tcg_gen_sari_i32(m, y, 16);
+       tcg_gen_andi_i32(m, m, 4);
+       /* n = n + m  */
+       tcg_gen_add_i32(n, n, m);
+       /* x = x << m  */
+       tcg_gen_shl_i32(x, x, m);
+
+       /* y = x - 0x4000  */
+       tcg_gen_subi_i32(y, x, 0x4000);
+       /* m = (y >> 16) & 2  */
+       tcg_gen_sari_i32(m, y, 16);
+       tcg_gen_andi_i32(m, m, 2);
+       /* n = n + m  */
+       tcg_gen_add_i32(n, n, m);
+       /* x = x << m  */
+       tcg_gen_shl_i32(x, x, m);
+
+       /* y = x >> 14  */
+       tcg_gen_shri_i32(y, x, 14);
+       /* m = y & ~(y >> 1)  */
+       tcg_gen_sari_i32(m, y, 1);
+       tcg_gen_xori_i32(m, m, 0xffffffff);
+       tcg_gen_and_i32(m, m, y);
+
+       /* d = n + 2 - m  */
+       tcg_gen_addi_i32(d, n, 2);
+       tcg_gen_sub_i32(d, d, m);
+
+       tcg_gen_discard_i32(y);
+       tcg_gen_discard_i32(m);
+       tcg_gen_discard_i32(n);
+}
+
 /* Extended arithmetics on CRIS.  */
 static inline void t_gen_add_flag(TCGv d, int flag)
 {
@@ -632,7 +700,7 @@ static void crisv32_alu_op(DisasContext *dc, int op, int rd, int size)
                        t_gen_subx_carry(cpu_T[0]);
                        break;
                case CC_OP_LZ:
-                       gen_op_lz_T0_T1();
+                       t_gen_lz_i32(cpu_T[0], cpu_T[1]);
                        break;
                case CC_OP_BTST:
                        gen_op_btst_T0_T1();