Re: [Qemu-devel] [PATCH 3/7] target-mips: add unions to access DSP elements

[Johnson, Eric]

> -----Original Message-----
> From: address@hidden [mailto:qemu-devel-
> address@hidden On Behalf Of Aurelien Jarno
> Sent: Friday, November 16, 2012 3:04 AM
> To: address@hidden
> Cc: Aurelien Jarno
> Subject: [Qemu-devel] [PATCH 3/7] target-mips: add unions to access DSP
> elements
> 
> Instead of playing with bit shifting, add two unions (one for 32-bit
> values, one for 64-bit ones) to access all the DSP elements with the
> correct type.
> 
> This make the code easier to read and less error prone, and allow GCC
> to vectorize the code in some cases.
> 
> Signed-off-by: Aurelien Jarno <address@hidden>
> ---
>  target-mips/dsp_helper.c |   22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/target-mips/dsp_helper.c b/target-mips/dsp_helper.c
> index e7949c2..8015d8d 100644
> --- a/target-mips/dsp_helper.c
> +++ b/target-mips/dsp_helper.c
> @@ -20,6 +20,28 @@
>  #include "cpu.h"
>  #include "helper.h"
> 
> +/* As the byte ordering doesn't matter, i.e. all columns are treated
> +   identically, these unions can be used directly.  */
> +typedef union {
> +    uint8_t  ub[4];
> +    int8_t   sb[4];
> +    uint16_t uh[2];
> +    int16_t  sh[2];
> +    uint32_t uw[1];
> +    int32_t  sw[1];
> +} DSP32Value;
> +
> +typedef union {
> +    uint8_t  ub[8];
> +    int8_t   sb[8];
> +    uint16_t uh[4];
> +    int16_t  sh[4];
> +    uint32_t uw[2];
> +    int32_t  sw[2];
> +    uint64_t ul[1];
> +    int64_t  sl[1];
> +} DSP64Value;
> +
>  /*** MIPS DSP internal functions begin ***/
>  #define MIPSDSP_ABS(x) (((x) >= 0) ? x : -x)
>  #define MIPSDSP_OVERFLOW(a, b, c, d) (!(!((a ^ b ^ -1) & (a ^ c) & d)))
> --
> 1.7.10.4
> 

Reviewed-by: Eric Johnson <address@hidden>