# Form `MD` — MD — Mask Double (rldicr/rldicl/rldic/rldimi)

## Bit Layout

| Bits | Field | Meaning |
| --- | --- | --- |
| 0–5 | `OPCD` | primary opcode (30) |
| 6–10 | `RS` | source GPR |
| 11–15 | `RA` | destination GPR |
| 16–20 | `sh` | shift amount low 5 bits |
| 21–26 | `mb/me` | 6-bit mask field (swapped halves) |
| 27–29 | `XO` | extended opcode |
| 30 | `sh5` | shift amount high bit |
| 31 | `Rc` | record-form flag |

## Instructions Using This Form

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| Mnemonic | Opcode | Group | Description |
| --- | --- | --- | --- |
| [`rldiclx`](../alu/rldiclx.md) | `0x78000000` | integer | Rotate Left Doubleword Immediate then Clear Left |
| [`rldicrx`](../alu/rldicrx.md) | `0x78000004` | integer | Rotate Left Doubleword Immediate then Clear Right |
| [`rldicx`](../alu/rldicx.md) | `0x78000008` | integer | Rotate Left Doubleword Immediate then Clear |
| [`rldimix`](../alu/rldimix.md) | `0x7800000c` | integer | Rotate Left Doubleword Immediate then Mask Insert |

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