diff options
| author | Philippe Mathieu-Daudé <philmd@linaro.org> | 2023-08-23 16:55:40 +0200 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2023-08-24 11:22:42 -0700 |
| commit | b8976aa5fe65e335af2eb5243a67d3b7fcd5442e (patch) | |
| tree | 76b5bbf901039bcb0d75a58284742ebed4eb0455 /tcg | |
| parent | 95180e750b16ab21556b1073c3051a848911093a (diff) | |
tcg/tcg-op: Document hswap_i32/64() byte pattern
Document hswap_i32() and hswap_i64(), added in commit
46be8425ff ("tcg: Implement tcg_gen_{h,w}swap_{i32,i64}").
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230823145542.79633-7-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'tcg')
| -rw-r--r-- | tcg/tcg-op.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c index 22c682c28e..58572526b7 100644 --- a/tcg/tcg-op.c +++ b/tcg/tcg-op.c @@ -1108,6 +1108,11 @@ void tcg_gen_bswap32_i32(TCGv_i32 ret, TCGv_i32 arg) } } +/* + * hswap_i32: Swap 16-bit halfwords within a 32-bit value. + * + * Byte pattern: abcd -> cdab + */ void tcg_gen_hswap_i32(TCGv_i32 ret, TCGv_i32 arg) { /* Swapping 2 16-bit elements is a rotate. */ @@ -1921,19 +1926,25 @@ void tcg_gen_bswap64_i64(TCGv_i64 ret, TCGv_i64 arg) } } +/* + * hswap_i64: Swap 16-bit halfwords within a 64-bit value. + * See also include/qemu/bitops.h, hswap64. + * + * Byte pattern: abcdefgh -> ghefcdab + */ void tcg_gen_hswap_i64(TCGv_i64 ret, TCGv_i64 arg) { uint64_t m = 0x0000ffff0000ffffull; TCGv_i64 t0 = tcg_temp_ebb_new_i64(); TCGv_i64 t1 = tcg_temp_ebb_new_i64(); - /* See include/qemu/bitops.h, hswap64. */ - tcg_gen_rotli_i64(t1, arg, 32); - tcg_gen_andi_i64(t0, t1, m); - tcg_gen_shli_i64(t0, t0, 16); - tcg_gen_shri_i64(t1, t1, 16); - tcg_gen_andi_i64(t1, t1, m); - tcg_gen_or_i64(ret, t0, t1); + /* arg = abcdefgh */ + tcg_gen_rotli_i64(t1, arg, 32); /* t1 = efghabcd */ + tcg_gen_andi_i64(t0, t1, m); /* t0 = ..gh..cd */ + tcg_gen_shli_i64(t0, t0, 16); /* t0 = gh..cd.. */ + tcg_gen_shri_i64(t1, t1, 16); /* t1 = ..efghab */ + tcg_gen_andi_i64(t1, t1, m); /* t1 = ..ef..ab */ + tcg_gen_or_i64(ret, t0, t1); /* ret = ghefcdab */ tcg_temp_free_i64(t0); tcg_temp_free_i64(t1); |