BFILL: Difference between revisions
Jump to navigation
Jump to search
m (Typo: Missing parenthesis.) |
(BFILL example 2 reworked to also show alternative page table mode) |
||
| (2 intermediate revisions by the same user not shown) | |||
| Line 39: | Line 39: | ||
A register = 1 | A register = 1 | ||
X register = 1 | X register = 1 | ||
T register = | T register = 0x0003 (bit 15 = 0, length field = 3) | ||
Memory area after execution: | Memory area after execution: | ||
| Line 47: | Line 47: | ||
3 0 0 | 3 0 0 | ||
X register = 2 | X register = 2 | ||
T register = | T register = 0x8000 (bit 15 = 1) | ||
P:= P+2 | P:= P+2 | ||
===Example 2=== | ===Example 2=== | ||
Memory area before execution, each address holds 2 bytes (1 word): | Memory area before execution, each address holds 2 bytes (1 word), work on alternative page table: | ||
Address: 0 0 0 | Address: 0 0 0 | ||
1 0 0 | 1 0 0 | ||
| Line 58: | Line 58: | ||
A register = 1 | A register = 1 | ||
X register = 1 | X register = 1 | ||
T register = | T register = 0xC003 (bit 15 = 1 (right byte), bit 14 = 1 (use APT), length field = 3) | ||
Memory area after execution: | Memory area after execution: | ||
| Line 66: | Line 66: | ||
3 0 0 | 3 0 0 | ||
X register = 3 | X register = 3 | ||
T register = | T register = 0x4000 (bit 15 = 0) | ||
P:= P+2 | P:= P+2 | ||
Latest revision as of 13:19, 26 July 2010
| BFILL | |
|---|---|
| Description | Byte fill |
| Format | BFILL |
| Code | 140 1308 |
| Affected | P,X,T, memory region defined by X,T |
| Type | User |
| Architecture | ND-100, ND-110 |
BFILL is an assembly instruction. A byte operand memory area defined by the X and T registers is filled with the value of the right-most byte in the A register.
The P register is incremented by two when this instruction is finished, i.e. any instruction directly following BFILL will not be executed.
The A, X and T registers should be set to appropriate values before execution of BFILL. The X and T registers will also be modified by the instruction.
- Before execution
A: Bit 0-7: The value to fill into each byte of the destination field.
X: Bit 0-15: The destination field's word address in memory.
T: Bit 15: This bit specifies whether the byte operand starts
in the left byte or right byte of the address defined by X.
Bit 15 = 0, left byte
Bit 15 = 1, right byte
Bit 14: Page table mode: Bit 14 = 1 selects the alternative page table.
Bit 13: This bit should be 0.
Bit 12: Not used.
Bit 11-0: Field length in number of bytes (0-4095).
- After execution
X: Bit 0-15: The word address of the byte following the last byte.
T: Bit 15: This bit specifies whether the byte following the last byte is
in the left byte or right byte of the address defined by X.
Bit 11-0: Set to zero.
Example 1
Memory area before execution, each address holds 2 bytes (1 word):
Address: 0 0 0
1 0 0
2 0 0
3 0 0
A register = 1
X register = 1
T register = 0x0003 (bit 15 = 0, length field = 3)
Memory area after execution:
Address: 0 0 0
1 1 1
2 1 0
3 0 0
X register = 2
T register = 0x8000 (bit 15 = 1)
P:= P+2
Example 2
Memory area before execution, each address holds 2 bytes (1 word), work on alternative page table:
Address: 0 0 0
1 0 0
2 0 0
3 0 0
A register = 1
X register = 1
T register = 0xC003 (bit 15 = 1 (right byte), bit 14 = 1 (use APT), length field = 3)
Memory area after execution:
Address: 0 0 0
1 0 1
2 1 1
3 0 0
X register = 3
T register = 0x4000 (bit 15 = 0)
P:= P+2
References
- Norsk Data Document ND–06.014.02 ND-100 REFERENCE MANUAL Pages 3-27,3-28
- Norsk Data Document ND–06.029.01 ND-110 Instruction Set Pages 92-93
The older document is more accurate for this instruction.