Re: [PATCH v3 3/4] target/s390x: implement CVB, CVBY and CVBG

[Thomas Huth]

On 01/02/2024 00.07, Ilya Leoshkevich wrote:
> From: Pavel Zbitskiy <pavel.zbitskiy@gmail.com>
>
> Convert to Binary - counterparts of the already implemented Convert
> to Decimal (CVD*) instructions.
> Example from the Principles of Operation: 25594C becomes 63FA.
>
> [iii: Use separate functions for CVB and CVBG for simplicity].
>
> Signed-off-by: Pavel Zbitskiy <pavel.zbitskiy@gmail.com>
> ---
>   target/s390x/helper.h            |  1 +
>   target/s390x/tcg/insn-data.h.inc |  4 ++++
>   target/s390x/tcg/int_helper.c    | 40 ++++++++++++++++++++++++++++++++
>   target/s390x/tcg/translate.c     | 12 ++++++++++
>   4 files changed, 57 insertions(+)
>
> diff --git a/target/s390x/helper.h b/target/s390x/helper.h
> index 332a9a9c632..3c607f4e437 100644
> --- a/target/s390x/helper.h
> +++ b/target/s390x/helper.h
> @@ -88,6 +88,7 @@ DEF_HELPER_FLAGS_3(tcxb, TCG_CALL_NO_RWG_SE, i32, env, i128, 
> i64)
>   DEF_HELPER_FLAGS_2(sqeb, TCG_CALL_NO_WG, i64, env, i64)
>   DEF_HELPER_FLAGS_2(sqdb, TCG_CALL_NO_WG, i64, env, i64)
>   DEF_HELPER_FLAGS_2(sqxb, TCG_CALL_NO_WG, i128, env, i128)
> +DEF_HELPER_FLAGS_3(cvb, TCG_CALL_NO_WG, i64, env, i64, i32)
>   DEF_HELPER_FLAGS_1(cvd, TCG_CALL_NO_RWG_SE, i64, s32)
>   DEF_HELPER_FLAGS_1(cvdg, TCG_CALL_NO_RWG_SE, i128, s64)
>   DEF_HELPER_FLAGS_4(pack, TCG_CALL_NO_WG, void, env, i32, i64, i64)
> diff --git a/target/s390x/tcg/insn-data.h.inc b/target/s390x/tcg/insn-data.h.inc
> index 388dcb8dbbc..9eb998d4c25 100644
> --- a/target/s390x/tcg/insn-data.h.inc
> +++ b/target/s390x/tcg/insn-data.h.inc
> @@ -293,6 +293,10 @@
>       D(0xec73, CLFIT,   RIE_a, GIE, r1_32u, i2_16u, 0, 0, ct, 0, 1)
>       D(0xec71, CLGIT,   RIE_a, GIE, r1_o, i2_16u, 0, 0, ct, 0, 1)
>   
> +/* CONVERT TO BINARY */
> +    C(0x4f00, CVB,     RX_a,  Z,   la2, 0, new, r1_32, cvb, 0)
> +    C(0xe306, CVBY,    RXY_a, LD,  la2, 0, new, r1_32, cvb, 0)
> +    C(0xe30e, CVBG,    RXY_a, Z,   la2, 0, r1, 0, cvbg, 0)
>   /* CONVERT TO DECIMAL */
>       C(0x4e00, CVD,     RX_a,  Z,   r1_o, a2, 0, 0, cvd, 0)
>       C(0xe326, CVDY,    RXY_a, LD,  r1_o, a2, 0, 0, cvd, 0)
> diff --git a/target/s390x/tcg/int_helper.c b/target/s390x/tcg/int_helper.c
> index 121e3006a65..002d4b52dda 100644
> --- a/target/s390x/tcg/int_helper.c
> +++ b/target/s390x/tcg/int_helper.c
> @@ -25,6 +25,7 @@
>   #include "exec/exec-all.h"
>   #include "qemu/host-utils.h"
>   #include "exec/helper-proto.h"
> +#include "exec/cpu_ldst.h"
>   
>   /* #define DEBUG_HELPER */
>   #ifdef DEBUG_HELPER
> @@ -98,6 +99,45 @@ Int128 HELPER(divu64)(CPUS390XState *env, uint64_t ah, 
> uint64_t al, uint64_t b)
>       tcg_s390_program_interrupt(env, PGM_FIXPT_DIVIDE, GETPC());
>   }
>   
> +uint64_t HELPER(cvb)(CPUS390XState *env, uint64_t src, uint32_t n)
> +{
> +    int64_t dec, sign = 0, digit, val = 0, pow10 = 0;
> +    const uintptr_t ra = GETPC();
> +    uint64_t tmpsrc;
> +    int i, j;
> +
> +    for (i = 0; i < n; i++) {
> +        tmpsrc = wrap_address(env, src + (n - i - 1) * 8);
> +        dec = cpu_ldq_data_ra(env, tmpsrc, ra);
> +        for (j = 0; j < 16; j++, dec >>= 4) {
> +            if (i == 0 && j == 0) {
> +                sign = dec & 0xf;
> +                if (sign < 0xa) {
> +                    tcg_s390_data_exception(env, 0, ra);
> +                }
> +                continue;
> +            }
> +            digit = dec & 0xf;
> +            if (digit > 0x9) {
> +                tcg_s390_data_exception(env, 0, ra);
> +            }
> +            if (i == 0 && j == 1) {
> +                if (sign == 0xb || sign == 0xd) {
> +                    val = -digit;
> +                    pow10 = -10;
> +                } else {
> +                    val = digit;
> +                    pow10 = 10;
> +                }
> +            } else {
> +                val += digit * pow10;
> +                pow10 *= 10;
> +            }
> +        }
> +    }
> +    return val;
> +}

I just noticed that there was even a v5 of Pavel's patch where David noted 
that the fixed-point-divide exception checks are still missing, see:

https://patchwork.kernel.org/project/qemu-devel/patch/20180902003322.3428-4-pavel.zbitskiy@gmail.com/ 


Could you add those, too, please?

 Thanks,
  Thomas