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 A primary critical use-case for extending FP is for 3D and supercomputing.
   9
  10 Publicly-known FP proposals:
  11
  12 * Zfrsqrt - Reciprocal SQRT <http://bugs.libre-riscv.org/show_bug.cgi?id=110>
  13 * Zftrans - see [[ztrans_proposal]]: Transcendentals
  14   (FSIN, FCOS, FATAN, FPOW, FEXP, FLOG, FRCP)
  15   <http://bugs.libre-riscv.org/show_bug.cgi?id=127>
  16 * Extension of formats to cover FP16 (RISC-V ISA Manual Table 11.3 "fmt field")
  17 * HI-half FP MV - <https://github.com/riscv/riscv-isa-manual/pull/301>
  18   <https://groups.google.com/a/groups.riscv.org/forum/m/#!topic/isa-dev/kXgfFqgBv-c>
  19 * (Add new entries here: Zextname - Description and URL)
  20
  21 [[!toc levels=2]]
  22
  23 # Main FP opcode 1010011 table
  24
  25 Notes:
  26
  27 * Proposed new encodings in **bold**.
  28 * *Use funct5 sparingly!* - 2-operand functions only.
  29 * Single-argument FP operations should go under one of the funct5 tables
  30 * Both dual and single argument FP operations that do not require
  31   "rounding mode" should go in one of the funct5 tables that already use
  32   "funct3".
  33 * The rs2 field can be best used to sub-select a considerable number
  34   of 1-op operations, with "rounding" in funct3
  35 * The funct3 field can be best used to sub-select a considerable number
  36   of 2-op operations
  37 * 1-op operations that do not need "rounding" have the best brownfield
  38   availability: 8 bit sub-selection (rs2=5 + funct3=3).  This however is
  39   rare as most FP operations need "rounding" selection.
  40 * Be careful not to use encoding space for which FP16 has already been
  41   reserved (mostly FP conversion opcodes)
  42
  43 [[!table  data="""
  44 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function       |
  45 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name           |
  46  5      | 2       | 5      | 5    | 3      | 5     |   7     |                |
  47 00000   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FADD.xx        |
  48 00001   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FSUB.xx        |
  49 00010   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FMUL.xx        |
  50 00011   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | FDIV.xx        |
  51 00100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  52 00101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=00101       |
  53 00110   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  54 00111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  55 01000   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=01000       |
  56 01001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  57 01010   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  58 01011   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=01011       |
  59 01100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  60 01101   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | **FATAN2.xx**  |
  61 01110   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | **FATAN2PI.xx**|
  62 01111   | xx      | rs2    | rs1  | rm     | rd    | 1010011 | **FPOW.xx**    |
  63 10000   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | **FROOT.xx**   |
  64 10001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  65 10010   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  66 10011   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  67 10100   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | tb=10100       |
  68 10101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  69 10110   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  70 10111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  71 11000   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11000       |
  72 11001   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  73 11010   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11010       |
  74 11100   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11100       |
  75 11101   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  76 11110   | xx      | xxxxx  | rs1  | yyy    | rd    | 1010011 | tb=11110       |
  77 11111   | xx      | rs2    | rs1  | yyy    | rd    | 1010011 | ?              |
  78 """]]
  79
  80 Code:
  81
  82 * xx: Opcode format field "fmt" - Table 11.3
  83 * xxxxx: 5-bit selection field (usually 1-op selection)
  84 * yyy: funct3 selection field (usually 2-op selection)
  85 * rm: "rounding mode"
  86
  87 ## funct5 = 00000 - FADD
  88
  89 No brownfield encodings available.
  90
  91 ## funct5 = 00001 - FSUB
  92
  93 No brownfield encodings available.
  94
  95 ## funct5 = 00010 - FMUL
  96
  97 No brownfield encodings available.
  98
  99 ## funct5 = 00011 - FDIV
 100
 101 No brownfield encodings available.
 102
 103 ## funct5 = 00100 - unused
 104
 105 Brownfield encodings available.
 106
 107 ## funct5 = 00100
 108
 109 This table uses funct3 for encoding 2-operand FP operations
 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 00100   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FSGNJ.xx    |
 116 00100   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FSGNJN.xx   |
 117 00100   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | FSGNJX.xx   |
 118 00100   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
 119 00100   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
 120 00100   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
 121 00100   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
 122 00100   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
 123 """]]
 124
 125 ## funct5 = 00101
 126
 127 This table uses funct3 for encoding 2-operand FP operations where the result
 128 register is a **floating-point** value.
 129
 130 [[!table  data="""
 131 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 132 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 133  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 134 00101   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FMIN.S      |
 135 00101   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FMAX.S      |
 136 00101   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | ?f3=010     |
 137 00101   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
 138 00101   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
 139 00101   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
 140 00101   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
 141 00101   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
 142 """]]
 143
 144 ## funct5 = 00110 - unused
 145
 146 Brownfield encodings available.
 147
 148 ## funct5 = 00111 - unused
 149
 150 Brownfield encodings available.
 151
 152 ## funct5 = 01000
 153
 154 This table uses rs2 for encoding 1-operand FP operations, using
 155 funct3 to specify the "rounding" mode
 156
 157 Notes:
 158
 159 * FP16 logically deduced from fmt field encoding (bits 25-26)
 160
 161 [[!table  data="""
 162 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 163 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 164  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 165 01000   | 00      | 00000  | rs1  | rm     | rd    | 1010011 | ????????    |
 166 01000   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.S.D    |
 167 01000   | 00      | 00010  | rs1  | rm     | rd    | 1010011 | **FCVT.S.H**|
 168 01000   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.S.Q    |
 169 01000   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 170 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 171 01000   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.D.S    |
 172 01000   | 01      | 00001  | rs1  | rm     | rd    | 1010011 | ????????    |
 173 01000   | 01      | 00010  | rs1  | rm     | rd    | 1010011 | **FCVT.D.H**|
 174 01000   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.D.Q    |
 175 01000   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 176 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 177 01000   | 10      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.H.S    |
 178 01000   | 10      | 00001  | rs1  | rm     | rd    | 1010011 | **FCVT.H.D**|
 179 01000   | 10      | 00010  | rs1  | rm     | rd    | 1010011 | ????????    |
 180 01000   | 10      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.H.Q    |
 181 01000   | 10      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 182 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 183 01000   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.Q.S    |
 184 01000   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.Q.D    |
 185 01000   | 11      | 00010  | rs1  | rm     | rd    | 1010011 | **FCVT.Q.H**|
 186 01000   | 11      | 00011  | rs1  | rm     | rd    | 1010011 | ????????    |
 187 01000   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 188 """]]
 189
 190 ## funct5 = 01001 - unused
 191
 192 Brownfield encodings available.
 193
 194 ## funct5 = 01010 - unused
 195
 196 Brownfield encodings available.
 197
 198 ## funct5 = 01011 - 1-op Transcendentals <a name="transcendentals_1op"></a>
 199
 200 This table uses rs2 for encoding 1-operand FP operations, using
 201 funct3 to specify the "rounding" mode
 202
 203 [[!table  data="""
 204 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function      |
 205 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name          |
 206  5      | 2       | 5      | 5    | 3      | 5     |   7     |               |
 207 01011   | xx      | 00000  | rs1  | rm     | rd    | 1010011 | FSQRT.xx      |
 208 01011   | xx      | 00001  | rs1  | rm     | rd    | 1010011 | **FRSQRT.xx** |
 209 01011   | xx      | 00010  | rs1  | rm     | rd    | 1010011 | **FRCP.xx**   |
 210 01011   | xx      | 00011  | rs1  | rm     | rd    | 1010011 | **FCBRT.xx**  |
 211 01011   | xx      | 00100  | rs1  | rm     | rd    | 1010011 | **FEXP2.xx**  |
 212 01011   | xx      | 00101  | rs1  | rm     | rd    | 1010011 | **FLOG2.xx**  |
 213 01011   | xx      | 00110  | rs1  | rm     | rd    | 1010011 | **FEXPM1.xx** |
 214 01011   | xx      | 00111  | rs1  | rm     | rd    | 1010011 | **FLOGP1.xx** |
 215 01011   | xx      | 01000  | rs1  | rm     | rd    | 1010011 | **FEXP.xx**   |
 216 01011   | xx      | 01001  | rs1  | rm     | rd    | 1010011 | **FLOG.xx**   |
 217 01011   | xx      | 01010  | rs1  | rm     | rd    | 1010011 | **FEXP10.xx** |
 218 01011   | xx      | 01011  | rs1  | rm     | rd    | 1010011 | **FLOG10.xx** |
 219 01011   | xx      | 01100  | rs1  | rm     | rd    | 1010011 | **FASINH.xx** |
 220 01011   | xx      | 01101  | rs1  | rm     | rd    | 1010011 | **FACOSH.xx** |
 221 01011   | xx      | 01110  | rs1  | rm     | rd    | 1010011 | **FATANH.xx** |
 222 01011   | xx      | 01111  | rs1  | rm     | rd    | 1010011 | ?             |
 223 01011   | xx      | 10000  | rs1  | rm     | rd    | 1010011 | **FSIN.xx**   |
 224 01011   | xx      | 10001  | rs1  | rm     | rd    | 1010011 | **FASIN.xx**  |
 225 01011   | xx      | 10010  | rs1  | rm     | rd    | 1010011 | **FSINPI.xx** |
 226 01011   | xx      | 10011  | rs1  | rm     | rd    | 1010011 | **FASINPI.xx**|
 227 01011   | xx      | 10100  | rs1  | rm     | rd    | 1010011 | **FCOS.xx**   |
 228 01011   | xx      | 10101  | rs1  | rm     | rd    | 1010011 | **FACOS.xx**  |
 229 01011   | xx      | 10110  | rs1  | rm     | rd    | 1010011 | **FCOSPI.xx** |
 230 01011   | xx      | 10111  | rs1  | rm     | rd    | 1010011 | **FACOSPI.xx**|
 231 01011   | xx      | 11000  | rs1  | rm     | rd    | 1010011 | **FTAN.xx**   |
 232 01011   | xx      | 11001  | rs1  | rm     | rd    | 1010011 | **FATAN.xx**  |
 233 01011   | xx      | 11010  | rs1  | rm     | rd    | 1010011 | **FTANPI.xx** |
 234 01011   | xx      | 11011  | rs1  | rm     | rd    | 1010011 | **FATANPI.xx**|
 235 01011   | xx      | 11100  | rs1  | rm     | rd    | 1010011 | **FSINH.xx**  |
 236 01011   | xx      | 11101  | rs1  | rm     | rd    | 1010011 | **FCOSH.xx**  |
 237 01011   | xx      | 11110  | rs1  | rm     | rd    | 1010011 | **FTANH.xx**  |
 238 01011   | xx      | 11111  | rs1  | rm     | rd    | 1010011 | ?             |
 239 """]]
 240
 241
 242
 243
 244
 245
 246
 247 ## funct5 = 01100 - unused
 248
 249 Brownfield encodings available.
 250
 251 ## funct5 = 01101 - **FATAN2**
 252
 253 Proposed for Zftrans - FATAN: "atan(rs1, rs2)"
 254
 255 ## funct5 = 01110 - **FATAN2PI**
 256
 257 Proposed for ZftransExt - FATAN2PI: "atan2(rs1, rs2) * PI".
 258 Rationale: Gives better accuracy than if using FMUL with the constant, PI.
 259
 260 ## funct5 = 01111 - **FPOW**
 261
 262 Proposed for ZftransAdv - FPOW: "FP rs1 to the power of rs2"
 263
 264 ## funct5 = 10000 - **FROOT**
 265
 266 Proposed for ZftransAdv - FPROOT: "FP rs1 to the power of (1/rs2)"
 267
 268 ## funct5 = 10000 - unused
 269
 270 Brownfield encodings available.
 271
 272 ## funct5 = 10001 - unused
 273
 274 Brownfield encodings available.
 275
 276 ## funct5 = 10010 - unused
 277
 278 Brownfield encodings available.
 279
 280 ## funct5 = 10011 - unused
 281
 282 Brownfield encodings available.
 283
 284 ## funct5 = 10100
 285
 286 This table uses funct3 for encoding 2-operand FP "comparison" operations
 287 where the result register is an **integer**
 288
 289 Notes:
 290
 291 * FNE missing?
 292
 293 [[!table  data="""
 294 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 295 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 296  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 297 10100   | xx      | rs2    | rs1  | 000    | rd    | 1010011 | FLE.xx      |
 298 10100   | xx      | rs2    | rs1  | 001    | rd    | 1010011 | FLT.xx      |
 299 10100   | xx      | rs2    | rs1  | 010    | rd    | 1010011 | FEQ.xx      |
 300 10100   | xx      | rs2    | rs1  | 011    | rd    | 1010011 | ?f3=011     |
 301 10100   | xx      | rs2    | rs1  | 100    | rd    | 1010011 | ?f3=100     |
 302 10100   | xx      | rs2    | rs1  | 101    | rd    | 1010011 | ?f3=101     |
 303 10100   | xx      | rs2    | rs1  | 110    | rd    | 1010011 | ?f3=110     |
 304 10100   | xx      | rs2    | rs1  | 111    | rd    | 1010011 | ?f3=111     |
 305 """]]
 306
 307 ## funct5 = 10101 - unused
 308
 309 Brownfield encodings available.
 310
 311 ## funct5 = 10110 - unused
 312
 313 Brownfield encodings available.
 314
 315 ## funct5 = 10111 - unused
 316
 317 Brownfield encodings available.
 318
 319 ## funct5 = 11000
 320
 321 This table uses rs2 for encoding 1-operand FP operations, using
 322 funct3 to specify the "rounding" mode
 323
 324 Notes:
 325
 326 * FP16 logically deduced from fmt field (bits 25-26)
 327
 328 [[!table  data="""
 329 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 330 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 331  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 332 11000   | 00      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.S    |
 333 11000   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.S   |
 334 11000   | 00      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.S    |
 335 11000   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.S   |
 336 11000   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 337 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 338 11000   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.D    |
 339 11000   | 01      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.D   |
 340 11000   | 01      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.D    |
 341 11000   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.D   |
 342 11000   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 343 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 344 11000   | 10      | 00000  | rs1  | rm     | rd    | 1010011 |**FCVT.W.H** |
 345 11000   | 10      | 00001  | rs1  | rm     | rd    | 1010011 |**FCVT.WU.H**|
 346 11000   | 10      | 00010  | rs1  | rm     | rd    | 1010011 |**FCVT.L.H** |
 347 11000   | 10      | 00011  | rs1  | rm     | rd    | 1010011 |**FCVT.LU.H**|
 348 11000   | 10      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 349 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 350 11000   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.W.Q    |
 351 11000   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.WU.Q   |
 352 11000   | 11      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.L.Q    |
 353 11000   | 11      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.LU.Q   |
 354 11000   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 355 """]]
 356
 357 ## funct5 = 11001 - unused
 358
 359 Brownfield encodings available.
 360
 361 ## funct5 = 11010
 362
 363 This table uses rs2 for encoding 1-operand FP operations, using
 364 funct3 to specify the "rounding" mode
 365
 366 * FP16 logically deduced from fmt field (bits 25-26)
 367
 368 [[!table  data="""
 369 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 370 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 371  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 372 11010   | 00      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.S.W    |
 373 11010   | 00      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.S.WU   |
 374 11010   | 00      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.S.L    |
 375 11010   | 00      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.S.LU   |
 376 11010   | 00      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 377 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 378 11010   | 01      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.D.W    |
 379 11010   | 01      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.D.WU   |
 380 11010   | 01      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.D.L    |
 381 11010   | 01      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.D.LU   |
 382 11010   | 01      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 383 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 384 11010   | 10      | 00000  | rs1  | rm     | rd    | 1010011 |**FCVT.H.W** |
 385 11010   | 10      | 00001  | rs1  | rm     | rd    | 1010011 |**FCVT.H.WU**|
 386 11010   | 10      | 00010  | rs1  | rm     | rd    | 1010011 |**FCVT.H.L** |
 387 11010   | 10      | 00011  | rs1  | rm     | rd    | 1010011 |**FCVT.H.LU**|
 388 11010   | 10      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 389 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 390 11010   | 11      | 00000  | rs1  | rm     | rd    | 1010011 | FCVT.Q.W    |
 391 11010   | 11      | 00001  | rs1  | rm     | rd    | 1010011 | FCVT.Q.WU   |
 392 11010   | 11      | 00010  | rs1  | rm     | rd    | 1010011 | FCVT.Q.L    |
 393 11010   | 11      | 00011  | rs1  | rm     | rd    | 1010011 | FCVT.Q.LU   |
 394 11010   | 11      | xxxxx  | rs1  | rm     | rd    | 1010011 | rs2?        |
 395 """]]
 396
 397 ## funct5 = 11100
 398
 399 This table uses *both* rs2 *and* funct3 for encoding 1-operand FP operations.
 400
 401 Notes:
 402
 403 * FMV.X.Q is missing (alias of FMVH.X.D if it existed)
 404 * FP16 logically deduced from fmt field (bits 25-26)
 405 * FMVH.X.HW (half-word) missing?
 406
 407 [[!table  data="""
 408 31..27| 26..25| 24..20 |19..15|14...12| 11..7 | 6....0  | function    |
 409 funct5| SDHQ  | rs2    | rs1  |funct3 | rd    | opcode  | name        |
 410  5    | 2     | 5      | 5    | 3     | 5     |   7     |             |
 411 11100 | 00    | 00000  | rs1  | 000   | rd    | 1010011 | FMV.X.W     |
 412 11100 | 00    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.S    |
 413 11100 | 00    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 414 ------| ----- | -----  | -----| ----- | ----- | ------- | --------    |
 415 11100 | 01    | 00000  | rs1  | 000   | rd    | 1010011 | FMV.X.D **FMVH.X.W** |
 416 11100 | 01    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.D    |
 417 11100 | 01    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 418 ------| ----- | -----  | -----| ----- | ----- | ------- | --------    |
 419 11100 | 10    | 00000  | rs1  | 000   | rd    | 1010011 |**FMV.X.H**  |
 420 11100 | 10    | 00000  | rs1  | 001   | rd    | 1010011 |**FCLASS.H** |
 421 11100 | 10    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 422 ------| ----- | -----  | -----| ----- | ----- | ------- | --------    |
 423 11100 | 11    | 00000  | rs1  | 000   | rd    | 1010011 | **FMVH.X.D** |
 424 11100 | 11    | 00000  | rs1  | 001   | rd    | 1010011 | FCLASS.Q    |
 425 11100 | xx    | xxxxx  | rs1  | yyy   | rd    | 1010011 | rs2? f3?    |
 426 """]]
 427
 428 ## funct5 = 11101 - unused
 429
 430 Brownfield encodings available.
 431
 432 ## funct5 = 11110
 433
 434 This table uses *both* rs2 *and* funct3 for encoding 1-operand FP operations.
 435
 436 Notes:
 437
 438 * FMV.Q.X is missing (as is FMVH.D.X)
 439 * FMVH.W.X is missing (alias of FMV.D.X)
 440 * FP16 logically deduced from fmt field (bits 25-26)
 441 * FMVH.HW.X (half-word) missing?
 442
 443 [[!table  data="""
 444 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 445 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 446  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 447 11110   | 00      | 00000  | rs1  | 000    | rd    | 1010011 | FMV.W.X     |
 448 11110   | 00      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 449 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 450 11110   | 01      | 00000  | rs1  | 000    | rd    | 1010011 | FMV.D.X     |
 451 11110   | 01      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 452 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 453 11110   | 10      | 00000  | rs1  | 000    | rd    | 1010011 |**FMV.H.X**  |
 454 11110   | 10      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 455 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 456 11110   | 11      | 00000  | rs1  | 000    | rd    | 1010011 | ?           |
 457 11110   | 11      | xxxxx  | rs1  | yyy    | rd    | 1010011 | rs2? f3?    |
 458 """]]
 459
 460 ## funct5 = 11111 - unused
 461
 462 Brownfield encodings available.
 463
 464 ## funct5 = ????? (table template)
 465
 466 This table acts as a cut/paste template for creating brownfield encodings
 467
 468 [[!table  data="""
 469 31..27  | 26..25  | 24..20 |19..15| 14...12| 11..7 | 6....0  | function    |
 470 funct5  | SDHQ    | rs2    | rs1  | funct3 | rd    | opcode  | name        |
 471  5      | 2       | 5      | 5    | 3      | 5     |   7     |             |
 472 ------  | -----   | -----  | -----| -----  | ----- | ------- | --------    |
 473 """]]
 474