target/mips: Amend MXU ASE overview note

Add prefix, suffix, operation descriptions, and other corrections
and amendments to the comment that describes MXU ASE.
Reviewed-by: NStefan Markovic <smarkovic@wavecomp.com>
Signed-off-by: NAleksandar Markovic <amarkovic@wavecomp.com>

target/mips/translate.c

@@ -1410,25 +1410,89 @@ 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:
+ * The notation used in MXU assembler mnemonics
+ * --------------------------------------------
+ *
+ *  Registers:
  *
  *   XRa, XRb, XRc, XRd - MXU registers
  *   Rb, Rc, Rd, Rs, Rt - general purpose MIPS registers
- *   s12                - a subfield of an instruction code
- *   strd2              - a subfield of an instruction code
- *   eptn2              - a subfield of an instruction code
- *   eptn3              - a subfield of an instruction code
- *   optn2              - a subfield of an instruction code
- *   optn3              - a subfield of an instruction code
- *   sft4               - a subfield of an instruction code
+ *
+ *  Subfields:
+ *
+ *   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
+ *
+ *  Operations:
+ *
+ *   ADD   - Add or subtract
+ *   ADDC  - Add with carry-in
+ *   ACC   - Accumulate
+ *   ASUM  - Sum together then accumulate (add or subtract)
+ *   ASUMC - Sum together then accumulate (add or subtract) with carry-in
+ *   AVG   - Average between 2 operands
+ *   ABD   - Absolute difference
+ *   ALN   - Align data
+ *   AND   - Logical bitwise 'and' operation
+ *   CPS   - Copy sign
+ *   EXTR  - Extract bits
+ *   I2M   - Move from GPR register to MXU register
+ *   LDD   - Load data from memory to XRF
+ *   LDI   - Load data from memory to XRF (and increase the address base)
+ *   LUI   - Load unsigned immediate
+ *   MUL   - Multiply
+ *   MULU  - Unsigned multiply
+ *   MADD  - 64-bit operand add 32x32 product
+ *   MSUB  - 64-bit operand subtract 32x32 product
+ *   MAC   - Multiply and accumulate (add or subtract)
+ *   MAD   - Multiply and add or subtract
+ *   MAX   - Maximum between 2 operands
+ *   MIN   - Minimum between 2 operands
+ *   M2I   - Move from MXU register to GPR register
+ *   MOVZ  - Move if zero
+ *   MOVN  - Move if non-zero
+ *   NOR   - Logical bitwise 'nor' operation
+ *   OR    - Logical bitwise 'or' operation
+ *   STD   - Store data from XRF to memory
+ *   SDI   - Store data from XRF to memory (and increase the address base)
+ *   SLT   - Set of less than comparison
+ *   SAD   - Sum of absolute differences
+ *   SLL   - Logical shift left
+ *   SLR   - Logical shift right
+ *   SAR   - Arithmetic shift right
+ *   SAT   - Saturation
+ *   SFL   - Shuffle
+ *   SCOP  - Calculate x’s scope (-1, means x<0; 0, means x==0; 1, means x>0)
+ *   XOR   - Logical bitwise 'exclusive or' operation
  *
  * Load/Store instructions           Multiplication instructions
  * -----------------------           ---------------------------
  *
  *  S32LDD XRa, Rb, s12               S32MADD XRa, XRd, Rs, Rt
  *  S32STD XRa, Rb, s12               S32MADDU XRa, XRd, Rs, Rt
- *  S32LDDV XRa, Rb, rc, strd2        S32SUB XRa, XRd, Rs, Rt
- *  S32STDV XRa, Rb, rc, strd2        S32SUBU XRa, XRd, Rs, Rt
+ *  S32LDDV XRa, Rb, rc, strd2        S32MSUB XRa, XRd, Rs, Rt
+ *  S32STDV XRa, Rb, rc, strd2        S32MSUBU XRa, XRd, Rs, Rt
  *  S32LDI XRa, Rb, s12               S32MUL XRa, XRd, Rs, Rt
  *  S32SDI XRa, Rb, s12               S32MULU XRa, XRd, Rs, Rt
  *  S32LDIV XRa, Rb, rc, strd2        D16MUL XRa, XRb, XRc, XRd, optn2