+
+/*
+ * This instruction performs 8-bit x 8-bit -> 16-bit signed multiplication
+ * and shifts the result one bit left.
+ */
+static bool trans_FMULSU(DisasContext *ctx, arg_FMULSU *a)
+{
+ if (!avr_have_feature(ctx, AVR_FEATURE_MUL)) {
+ return true;
+ }
+
+ TCGv R0 = cpu_r[0];
+ TCGv R1 = cpu_r[1];
+ TCGv Rd = cpu_r[a->rd];
+ TCGv Rr = cpu_r[a->rr];
+ TCGv R = tcg_temp_new_i32();
+ TCGv t0 = tcg_temp_new_i32();
+
+ tcg_gen_ext8s_tl(t0, Rd); /* make Rd full 32 bit signed */
+ tcg_gen_mul_tl(R, t0, Rr); /* R = Rd * Rr */
+ tcg_gen_andi_tl(R, R, 0xffff); /* make it 16 bits */
+
+ tcg_gen_shri_tl(cpu_Cf, R, 15); /* Cf = R(15) */
+ tcg_gen_setcondi_tl(TCG_COND_EQ, cpu_Zf, R, 0); /* Zf = R == 0 */
+
+ tcg_gen_shli_tl(R, R, 1);
+
+ tcg_gen_andi_tl(R0, R, 0xff);
+ tcg_gen_shri_tl(R1, R, 8);
+ tcg_gen_andi_tl(R1, R1, 0xff);
+
+ tcg_temp_free_i32(t0);
+ tcg_temp_free_i32(R);
+
+ return true;
+}
+
Hi, Michael.
The way I understand the spec is that a->rd and a->rd must be between 16 and 23:
Is my interpretation right? If yes, where is the corresponding part in the implementation?