Sign extension unit
AssigneeKabushiki Kaisha Toshiba
InventorsNaoyuki Tamura, Takeshi Yoshida
Life of this patent
Estimating the term…
Abstract
A sign extension unit has first and second sign extenders to extend a sign bit, i.e., the most significant bit of input data to the higher side of the input data. The input data is divided into n-bit blocks. The first sign extender carries out sign extension based on highest bits of the blocks, and the second sign extender carries out sign extension in each of the blocks based on the highest bits of the respective blocks.
Claims7
A sign extension unit for extending a sign bit of input data and generating signed output data, the input data consisting of input bits that are divided into blocks, the sign extension unit comprising:
- a first sign extender for receiving highest bits from the blocks, selecting at least one of the received bits according to the bit length of the input data with the sign bit being always selected, and providing the selected at least one bit as a highest bit from the blocks;
- and
- a second sign extender for receiving the bits of the blocks except those of a lowest one of the blocks and for receiving the selected at least one bit from the first sign extender, selecting, in each of the blocks except the lowest block, the highest bit of the block or the bits of the block according to the bit length of the input data, and providing the selected bits.
A sign extension unit for extending a sign bit of input data to the higher side of the input data and generating signed output data, the input data consisting of input bits which are divided into blocks and among which the most significant one is the sign bit of the input data, the sign extension unit comprising:
- a first sign extender for receiving juxtaposed highest bits from the blocks, selecting at least one of the received bits according to the bit length of the input data with the sign bit being always selected, and extending the sign bit for the highest bits of the blocks that are higher than the block that contains the sign bit;
- and
- a second sign extender for receiving the juxtaposed bits of the blocks except those of a lowest one of the blocks and for receiving the extended sign bit for the highest bits of the blocks as provided by the first sign extender, selecting, in each of the blocks except the lowest block, the highest bit of the block or the bits of the block according to the bit length of the input data, and extending the sign bit for all bits in each of the blocks having the highest bits for which the first sign extender has extended the sign bit.
A sign extension unit for extending a sign bit of input data to the higher side of the input data and generating signed 64-bit output data consisting of bit 0 to bit 63, the input data consisting of 8, 16, 32, or 64 input bits which are grouped from the least significant bit thereof into 8-bit blocks ranging from block 0 to block 7, the most significant bit of the input bits being the sign bit of the input data, the sign extension unit comprising:
- a first extender for receiving juxtaposed highest bits (8m−1;
- m=1, 2, . . . , 8) from the blocks, extending a bit 7 of the input data for the highest bits (8m−1;
- m=2, 3, . . . , 8) of the blocks 1 to 7 if the input data consists of 8 bits ranging from bit 0 to bit 7, extending a bit 15 of the input data for the highest bits (8m−1;
- m=3, 4, . . . , 8) of the blocks 2 to 7 if the input data consists of 16 bits ranging from bit 0 to bit 15, and extending a bit 31 of the input data for the highest bits (8m−1;
- m=5, 6, . . . , 8) of the blocks 4 to 7 if the input data consists of 32 bits ranging from bit 0 to bit 31;
- and
- a second extender for receiving any extended bits from the first extender and for receiving juxtaposed bits from the blocks 1 to 7, extending the bits (8m−1;
- m=2, 3, . . . , 8) of the blocks 1 to 7 to the bits (8n+6;
- n=1, 2, . . . , 7) of the same blocks if the input data consists of 8 bits, extending the bits (8m−1;
- m=3, 4, . . . , 8) of the blocks 2 to 7 to the bits (8n+6;
- n=2, 3, . . . , 7) of the same blocks if the input data consists of 16 bits, and extending the bits (8m−1;
- m=5, 6, . . . , 8) of the blocks 4 to 7 to the bits (8n+6;
- n=4, 5, . . . , 7) of the same blocks if the input data consists of 32 bits.
Dependencies are inferred from the claim text.