Re: [Qemu-devel] [PATCH 3/6] target/mips: MXU: Improve textual description

[Stefan Markovic <smarkovic@wavecomp.com>]

On 17.12.18. 21:04, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <amarkovic@wavecomp.com>
>
> Improve textual description of MXU extension. These are mostly
> comment formatting changes.
>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>   target/mips/translate.c | 74 ++++++++++++++++++++++++-----------------
>   1 file changed, 44 insertions(+), 30 deletions(-)


Reviewed-by: Stefan Markovic <smarkovic@wavecomp.com>


> diff --git a/target/mips/translate.c b/target/mips/translate.c
> index 74d16ce52e..e3a5a73e59 100644
> --- a/target/mips/translate.c
> +++ b/target/mips/translate.c
> @@ -1399,10 +1399,12 @@ enum {
>   
>   
>   /*
> - *    AN OVERVIEW OF MXU EXTENSION INSTRUCTION SET
> - *    ============================================
>    *
> - * MXU (full name: MIPS eXtension/enhanced Unit) is an SIMD extension of MIPS32
> + *       AN OVERVIEW OF MXU EXTENSION INSTRUCTION SET
> + *       ============================================
> + *
> + *
> + * MXU (full name: MIPS eXtension/enhanced Unit) is a SIMD extension of MIPS32
>    * instructions set. It is designed to fit the needs of signal, graphical and
>    * video processing applications. MXU instruction set is used in Xburst family
>    * of microprocessors by Ingenic.
> @@ -1410,39 +1412,31 @@ enum {
>    * MXU unit contains 17 registers called X0-X16. X0 is always zero, and X16 is
>    * the control register.
>    *
> - * The notation used in MXU assembler mnemonics
> - * --------------------------------------------
>    *
> - *  Registers:
> + *     The notation used in MXU assembler mnemonics
> + *     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + *  Register operands:
>    *
>    *   XRa, XRb, XRc, XRd - MXU registers
>    *   Rb, Rc, Rd, Rs, Rt - general purpose MIPS registers
>    *
> - *  Subfields:
> + *  Non-register operands:
>    *
> - *   aptn1              - 1-bit accumulate add/subtract pattern
> - *   aptn2              - 2-bit accumulate add/subtract pattern
> - *   eptn2              - 2-bit execute add/subtract pattern
> - *   optn2              - 2-bit operand pattern
> - *   optn3              - 3-bit operand pattern
> - *   sft4               - 4-bit shift amount
> - *   strd2              - 2-bit stride amount
> + *   aptn1 - 1-bit accumulate add/subtract pattern
> + *   aptn2 - 2-bit accumulate add/subtract pattern
> + *   eptn2 - 2-bit execute add/subtract pattern
> + *   optn2 - 2-bit operand pattern
> + *   optn3 - 3-bit operand pattern
> + *   sft4  - 4-bit shift amount
> + *   strd2 - 2-bit stride amount
>    *
>    *  Prefixes:
>    *
> - *   <Operation parallel level><Operand size>
> - *     S                         32
> - *     D                         16
> - *     Q                          8
> - *
> - *  Suffixes:
> - *
> - *   E - Expand results
> - *   F - Fixed point multiplication
> - *   L - Low part result
> - *   R - Doing rounding
> - *   V - Variable instead of immediate
> - *   W - Combine above L and V
> + *   Level of parallelism:                Operand size:
> + *    S - single operation at a time       32 - word
> + *    D - two operations in parallel       16 - half word
> + *    Q - four operations in parallel       8 - byte
>    *
>    *  Operations:
>    *
> @@ -1486,6 +1480,19 @@ enum {
>    *   SCOP  - Calculate x’s scope (-1, means x<0; 0, means x==0; 1, means x>0)
>    *   XOR   - Logical bitwise 'exclusive or' operation
>    *
> + *  Suffixes:
> + *
> + *   E - Expand results
> + *   F - Fixed point multiplication
> + *   L - Low part result
> + *   R - Doing rounding
> + *   V - Variable instead of immediate
> + *   W - Combine above L and V
> + *
> + *
> + *     The list of MXU instructions grouped by functionality
> + *     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
>    * Load/Store instructions           Multiplication instructions
>    * -----------------------           ---------------------------
>    *
> @@ -1563,6 +1570,13 @@ enum {
>    *  Q16SAT XRa, XRb, XRc              S32I2M XRa, Rb
>    *
>    *
> + *     The opcode organization of MXU instructions
> + *     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + * The bits 31..26 of all MXU instructions are equal to 0x1C (also referred
> + * as opcode SPECIAL2 in the base MIPS ISA). The organization and meaning of
> + * other bits up to the instruction level is as follows:
> + *
>    *              bits
>    *             05..00
>    *
> @@ -1700,7 +1714,7 @@ enum {
>    *          │                            ├─ 010 ─ OPC_MXU_D16MOVZ
>    *          │                            ├─ 011 ─ OPC_MXU_D16MOVN
>    *          │                            ├─ 100 ─ OPC_MXU_S32MOVZ
> - *          │                            └─ 101 ─ OPC_MXU_S32MOV
> + *          │                            └─ 101 ─ OPC_MXU_S32MOVN
>    *          │
>    *          │                               23..22
>    *          ├─ 111010 ─ OPC_MXU__POOL21 ─┬─ 00 ─ OPC_MXU_Q8MAC
> @@ -1712,10 +1726,10 @@ enum {
>    *          └─ 111111 ─ <not assigned>   (overlaps with SDBBP)
>    *
>    *
> - *   Compiled after:
> + * Compiled after:
>    *
>    *   "XBurst® Instruction Set Architecture MIPS eXtension/enhanced Unit
> - *   Programming Manual", Ingenic Semiconductor Co, Ltd., 2017
> + *   Programming Manual", Ingenic Semiconductor Co, Ltd., revision June 2, 2017
>    */
>   
>   enum {