rv_major_opcode_1010011.mdwn

   1 # Summary FP Opcodes
   2
   3 This page aids and assists in the development of FP proposals,
   4 by identifying and listing in full both publicly-known proposals
   5 and the full brownfield encoding space available in the 0b010011
   6 major opcode.
   7
   8 Publicly-known FP proposals:
   9
  10 * Zfrsqrt - Reciprocal SQRT <http://bugs.libre-riscv.org/show_bug.cgi?id=110>
  11 * Zftrans - Transcendentals (FSIN, FCOS, FATAN, FPOW, FEXP, FLOG, FRCP)
  12 * HI-half FP MV - <https://github.com/riscv/riscv-isa-manual/pull/301>
  13   <https://groups.google.com/a/groups.riscv.org/forum/m/#!topic/isa-dev/kXgfFqgBv-c>
  14 * (Add new entries here: Zextname - Description and URL)
  15
  16 [[!toc levels=2]]
  17
  18 # Main FP opcode 1010011 table
  19
  20 Notes:
  21
  22 * Proposed new encodings in **bold**.
  23 * *Use funct5 sparingly!* - 2-operand functions only.
  24 * Single-argument FP operations should go under one of the funct5 tables
  25 * Both dual and single argument FP operations that do not require
  26   "rounding mode" should go in one of the funct5 tables that already use
  27   "funct3".
  28 * Be careful not to use encoding space for which FP16 has already been
  29   reserved.
  30
  31 [[!table  data="""
  32 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
  33 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
  34  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
  35 00000   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FADD.xx     |
  36 00001   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FSUB.xx     |
  37 00010   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FMUL.xx     |
  38 00011   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FDIV.xx     |
  39 00100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  40 00101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=00101    |
  41 00110   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  42 00111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  43 01000   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=01000    |
  44 01001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  45 01010   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  46 01011   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=01011    |
  47 01100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  48 01101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  49 01110   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  50 01111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | **FPOW.xx** |
  51 10000   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  52 10001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  53 10010   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  54 10011   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  55 10100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=10100    |
  56 10101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  57 10110   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  58 10111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  59 11000   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11000    |
  60 11001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  61 11010   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11010    |
  62 11100   | xx      | xxxxx  | rs1  | 000    | rd    | 1010011 | tb=11100    |
  63 11101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  64 11110   | xx      | xxxxx  | rs1  | 000    | rd    | 1010011 | tb=11110    |
  65 11111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?           |
  66 """]]
  67
  68 ## funct5 = 00100
  69
  70 This table uses funct3 for encoding 2-operand FP operations
  71
  72 [[!table  data="""
  73 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
  74 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
  75  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
  76 00100   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FSGNJ.xx    |
  77 00100   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FSGNJN.xx   |
  78 00100   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | FSGNJX.xx   |
  79 00100   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
  80 00100   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
  81 00100   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
  82 00100   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
  83 00100   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
  84 """]]
  85
  86 ## funct5 = 00000 - FADD
  87
  88 No brownfield encodings available.
  89
  90 ## funct5 = 00001 - FSUB
  91
  92 No brownfield encodings available.
  93
  94 ## funct5 = 00010 - FMUL
  95
  96 No brownfield encodings available.
  97
  98 ## funct5 = 00011 - FDIV
  99
 100 No brownfield encodings available.
 101
 102 ## funct5 = 00100 - unused
 103
 104 Brownfield encodings available.
 105
 106 ## funct5 = 00101
 107
 108 This table uses funct3 for encoding 2-operand FP operations where the result
 109 register is a **floating-point** value.
 110
 111 [[!table  data="""
 112 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 113 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 114  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 115 00101   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FMIN.S      |
 116 00101   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FMAX.S      |
 117 00101   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | ?f3=010     |
 118 00101   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
 119 00101   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
 120 00101   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
 121 00101   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
 122 00101   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
 123 """]]
 124
 125 ## funct5 = 00110 - unused
 126
 127 Brownfield encodings available.
 128
 129 ## funct5 = 00111 - unused
 130
 131 Brownfield encodings available.
 132
 133 ## funct5 = 01000
 134
 135 This table uses rs2 for encoding 1-operand FP operations that require "rounding"
 136
 137 Notes:
 138
 139 * TODO FP16 (trivial)
 140
 141
 142 [[!table  data="""
 143 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 144 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 145  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 146 01000   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.S.D    |
 147 01000   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.S.Q    |
 148 01000   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 149 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 150 01000   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.D.S    |
 151 01000   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.D.Q    |
 152 01000   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 153 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 154 01000   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.Q.S    |
 155 01000   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.Q.D    |
 156 01000   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 157 """]]
 158
 159 ## funct5 = 01001 - unused
 160
 161 Brownfield encodings available.
 162
 163 ## funct5 = 01010 - unused
 164
 165 Brownfield encodings available.
 166
 167 ## funct5 = 01011
 168
 169 This table uses rs2 for encoding 1-operand FP operations that require "rounding"
 170
 171 [[!table  data="""
 172 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function      |
 173 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name          |
 174  5      | 2       | 5      | 5    | 3      | 5     |   7     |               |
 175 01011   | xx      | 00000  | rs1  | rm     | rd    | 1010011 | FSQRT.xx      |
 176 01011   | xx      | 00001  | rs1  | rm     | rd    | 1010011 | **FRSQRT.xx** |
 177 01011   | xx      | 00010  | rs1  | rm     | rd    | 1010011 | **FSIN.xx**   |
 178 01011   | xx      | 00011  | rs1  | rm     | rd    | 1010011 | **FCOS.xx**   |
 179 01011   | xx      | 00100  | rs1  | rm     | rd    | 1010011 | **FATAN.xx**  |
 180 01011   | xx      | 00101  | rs1  | rm     | rd    | 1010011 | **FEXP.xx**   |
 181 01011   | xx      | 00110  | rs1  | rm     | rd    | 1010011 | **FLOG.xx**   |
 182 01011   | xx      | 00111  | rs1  | rm     | rd    | 1010011 | **FRCP.xx**   |
 183 01011   | xx      | 01000  | rs1  | rm     | rd    | 1010011 | ?             |
 184 01011   | xx      | 01001  | rs1  | rm     | rd    | 1010011 | ?             |
 185 01011   | xx      | 01010  | rs1  | rm     | rd    | 1010011 | ?             |
 186 01011   | xx      | 01011  | rs1  | rm     | rd    | 1010011 | ?             |
 187 01011   | xx      | 01100  | rs1  | rm     | rd    | 1010011 | ?             |
 188 01011   | xx      | 01101  | rs1  | rm     | rd    | 1010011 | ?             |
 189 01011   | xx      | 01110  | rs1  | rm     | rd    | 1010011 | ?             |
 190 01011   | xx      | 01111  | rs1  | rm     | rd    | 1010011 | ?             |
 191 01011   | xx      | 10000  | rs1  | rm     | rd    | 1010011 | ?             |
 192 01011   | xx      | 10001  | rs1  | rm     | rd    | 1010011 | ?             |
 193 01011   | xx      | 10010  | rs1  | rm     | rd    | 1010011 | ?             |
 194 01011   | xx      | 10011  | rs1  | rm     | rd    | 1010011 | ?             |
 195 01011   | xx      | 10100  | rs1  | rm     | rd    | 1010011 | ?             |
 196 01011   | xx      | 10101  | rs1  | rm     | rd    | 1010011 | ?             |
 197 01011   | xx      | 10110  | rs1  | rm     | rd    | 1010011 | ?             |
 198 01011   | xx      | 10111  | rs1  | rm     | rd    | 1010011 | ?             |
 199 01011   | xx      | 11000  | rs1  | rm     | rd    | 1010011 | ?             |
 200 01011   | xx      | 11001  | rs1  | rm     | rd    | 1010011 | ?             |
 201 01011   | xx      | 11010  | rs1  | rm     | rd    | 1010011 | ?             |
 202 01011   | xx      | 11011  | rs1  | rm     | rd    | 1010011 | ?             |
 203 01011   | xx      | 11100  | rs1  | rm     | rd    | 1010011 | ?             |
 204 01011   | xx      | 11101  | rs1  | rm     | rd    | 1010011 | ?             |
 205 01011   | xx      | 11110  | rs1  | rm     | rd    | 1010011 | ?             |
 206 01011   | xx      | 11111  | rs1  | rm     | rd    | 1010011 | ?             |
 207 """]]
 208
 209 ## funct5 = 01100 - unused
 210
 211 Brownfield encodings available.
 212
 213 ## funct5 = 01101 - unused
 214
 215 Brownfield encodings available.
 216
 217 ## funct5 = 01110 - unused
 218
 219 Brownfield encodings available.
 220
 221 ## funct5 = 01111 - **FPOW**
 222
 223 Proposed for Zftrans - FPOW: "FP rs2 to the power of rs1"
 224
 225 ## funct5 = 10000 - unused
 226
 227 Brownfield encodings available.
 228
 229 ## funct5 = 10001 - unused
 230
 231 Brownfield encodings available.
 232
 233 ## funct5 = 10010 - unused
 234
 235 Brownfield encodings available.
 236
 237 ## funct5 = 10011 - unused
 238
 239 Brownfield encodings available.
 240
 241 ## funct5 = 10100
 242
 243 This table uses funct3 for encoding 2-operand FP "comparison" operations
 244 where the result register is an **integer**
 245
 246 Notes:
 247
 248 * FNE missing?
 249
 250 [[!table  data="""
 251 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 252 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 253  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 254 10100   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FLE.xx      |
 255 10100   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FLT.xx      |
 256 10100   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | FEQ.xx      |
 257 10100   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
 258 10100   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
 259 10100   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
 260 10100   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
 261 10100   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
 262 """]]
 263
 264 ## funct5 = 10101 - unused
 265
 266 Brownfield encodings available.
 267
 268 ## funct5 = 10110 - unused
 269
 270 Brownfield encodings available.
 271
 272 ## funct5 = 10111 - unused
 273
 274 Brownfield encodings available.
 275
 276 ## funct5 = 11000
 277
 278 This table uses rs2 for encoding 1-operand FP operations that require "rounding"
 279
 280 Notes:
 281
 282 * TODO FP16 (trivial)
 283
 284 [[!table  data="""
 285 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 286 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 287  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 288 11000   | 00      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.S    |
 289 11000   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.S   |
 290 11000   | 00      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.S    |
 291 11000   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.S   |
 292 11000   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 293 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 294 11000   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.D    |
 295 11000   | 01      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.D   |
 296 11000   | 01      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.D    |
 297 11000   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.D   |
 298 11000   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 299 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 300 11000   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.Q    |
 301 11000   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.Q   |
 302 11000   | 11      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.Q    |
 303 11000   | 11      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.Q   |
 304 11000   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 305 """]]
 306
 307 ## funct5 = 11001 - unused
 308
 309 Brownfield encodings available.
 310
 311 ## funct5 = 11010
 312
 313 This table uses rs2 for encoding 1-operand FP operations that require "rounding"
 314
 315 [[!table  data="""
 316 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 317 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 318  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 319 11010   | 00      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.S.W    |
 320 11010   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.S.WU   |
 321 11010   | 00      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.S.L    |
 322 11010   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.S.LU   |
 323 11010   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 324 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 325 11010   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.D.W    |
 326 11010   | 01      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.D.WU   |
 327 11010   | 01      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.D.L    |
 328 11010   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.D.LU   |
 329 11010   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 330 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 331 11010   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.Q.W    |
 332 11010   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.Q.WU   |
 333 11010   | 11      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.Q.L    |
 334 11010   | 11      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.Q.LU   |
 335 11010   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 336 """]]
 337
 338 ## funct5 = 11100
 339
 340 This table uses *both* rs2 *and* funct3 for encoding 1-operand FP operations.
 341
 342 Notes:
 343
 344 * FMV.X.Q is missing (alias of FMVH.X.D if it existed)
 345 * TODO FP16 (trivial)
 346 * FMVH.X.HW (half-word) missing?
 347
 348 [[!table  data="""
 349 31..27| 26..25| 24..20 |19..15|14...12| 11..7 | 6....0  | function    |
 350 funct5| SDHQ  | rs2    | rs1  |funct3 | rd    | opcode  | name        |
 351  5    | 2     | 5      | 5    | 3     | 5     |   7     |             |
 352 11100 | 00    | 00000  | rs1  | 000   | rd    | 1010011 | FMV.X.W     |
 353 11100 | 00    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.S    |
 354 11100 | 00    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 355 ------| ----- | -----  | -----| ----- | ----- | ------- | --------    |
 356 11100 | 01    | 00000  | rs1  | 000   | rd    | 1010011 | FMV.X.D **FMVH.X.W** |
 357 11100 | 01    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.D    |
 358 11100 | xx    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 359 ------| ----- | -----  | -----| ----- | ----- | ------- | --------    |
 360 11100 | 11    | 00000  | rs1  | 000   | rd    | 1010011 | **FMVH.X.D** |
 361 11100 | 11    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.Q    |
 362 11100 | xx    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 363 """]]
 364
 365 ## funct5 = 11101 - unused
 366
 367 Brownfield encodings available.
 368
 369 ## funct5 = 11110
 370
 371 This table uses *both* rs2 *and* funct3 for encoding 1-operand FP operations.
 372
 373 Notes:
 374
 375 * FMV.Q.X is missing (as is FMVH.D.X)
 376 * FMVH.W.X is missing (alias of FMV.D.X)
 377 * TODO FP16 (trivial)
 378 * FMVH.HW.X (half-word) missing?
 379
 380 [[!table  data="""
 381 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 382 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 383  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 384 11110   | 00      | 00000  | rs1  | 000    | rd    | 1010011 | FMV.W.X     |
 385 11110   | 00      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 386 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 387 11110   | 01      | 00000  | rs1  | 000    | rd    | 1010011 | FMV.D.X     |
 388 11110   | 01      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 389 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 390 11110   | 11      | 00000  | rs1  | 000    | rd    | 1010011 | ?           |
 391 11110   | 11      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 392 """]]
 393
 394 ## funct5 = 11111 - unused
 395
 396 Brownfield encodings available.
 397
 398 ## funct5 = ?????
 399
 400 [[!table  data="""
 401 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 402 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 403  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 404 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 405 """]]
 406