Re: [Qemu-devel] [PATCH v2 01/17] RISC-V: add vfp field in CPURISCVState

[Chih-Min Chao]

On Wed, Sep 11, 2019 at 2:35 PM liuzhiwei <address@hidden> wrote:

> From: LIU Zhiwei <address@hidden>
>
> Signed-off-by: LIU Zhiwei <address@hidden>
> ---
>  target/riscv/cpu.h | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 0adb307..c992b1d 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -93,9 +93,37 @@ typedef struct CPURISCVState CPURISCVState;
>
>  #include "pmp.h"
>
> +#define VLEN 128
> +#define VUNIT(x) (VLEN / x)
> +
>  struct CPURISCVState {
>      target_ulong gpr[32];
>      uint64_t fpr[32]; /* assume both F and D extensions */
> +
> +    /* vector coprocessor state.  */
> +    struct {
> +        union VECTOR {
> +            float64  f64[VUNIT(64)];
> +            float32  f32[VUNIT(32)];
> +            float16  f16[VUNIT(16)];
> +            uint64_t u64[VUNIT(64)];
> +            int64_t  s64[VUNIT(64)];
> +            uint32_t u32[VUNIT(32)];
> +            int32_t  s32[VUNIT(32)];
> +            uint16_t u16[VUNIT(16)];
> +            int16_t  s16[VUNIT(16)];
> +            uint8_t  u8[VUNIT(8)];
> +            int8_t   s8[VUNIT(8)];
> +        } vreg[32];
> +        target_ulong vxrm;
> +        target_ulong vxsat;
> +        target_ulong vl;
> +        target_ulong vstart;
> +        target_ulong vtype;
> +        float_status fp_status;
> +    } vfp;
> +
> +    bool         foflag;
>      target_ulong pc;
>      target_ulong load_res;
>      target_ulong load_val;
> --
> 2.7.4
>
>
Could  the VLEN be configurable in cpu initialization but not fixed in
compilation phase ?
Take the integer element as example  and the difference should be the
stride of vfp.vreg[x] isn't continuous

    struct {
        union VECTOR {
            uint64_t *u64;
            uint16_t *u16;
            uint8_t  *u8;
        } vreg[32];
    } vfp;

   initialization

    int vlen = 256;  //parameter from cpu command line option
    int elem = vlen / 8;
    int size = elem * 32;

    uint8_t *mem = malloc(size)
    for (int idx = 0; idx < 32; ++idx) {
        vfp.vreg[idx].u64 = (void *)&mem[idx * elem];
        vfp.vreg[idx].u32 = (void *)&mem[idx * elem];
        vfp.vreg[idx].u16 = (void *)&mem[idx * elem];
   }

  chihmin