On 8/30/21 4:15 AM, Philipp Tomsich wrote:
+ TCGv tmp = tcg_temp_new();
+
+ /* Set msb in each byte if the byte was zero. */
+ tcg_gen_subi_tl(tmp, source1, dup_const(MO_8, 0x01));
+ tcg_gen_andc_tl(tmp, tmp, source1);
+ tcg_gen_andi_tl(tmp, tmp, dup_const(MO_8, 0x80));
+
+ /* Replicate the msb of each byte across the byte. */
+ tcg_gen_shri_tl(tmp, tmp, 7);
+ tcg_gen_muli_tl(tmp, tmp, 0xff);
+
+ /* Negate */
+ tcg_gen_not_tl(ret, tmp);
It just occurred to me that we can swap the shift/andi and re-use the same constant, and
we can fold in the negate with andc.
TCGv ones = tcg_constant_tl(dup_const(MO_8, 1));
TCGv tmp = tcg_temp_new();
tcg_gen_sub_tl(tmp, src1, ones);
tcg_gen_andc_tl(tmp, tmp, src1);
tcg_gen_shri_tl(tmp, tmp, 7);
tcg_gen_andc_tl(tmp, ones, tmp);
tcg_gen_muli_tl(tmp, tmp, 0xff);
tcg_temp_free(tmp);
r~
