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SSSE3

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Not to be confused with SSE3.

Supplemental Streaming SIMD Extensions 3 (SSSE3 or SSE3S) is a SIMD instruction set created by Intel and is the fourth iteration of the SSE technology.

History

SSSE3 was first introduced with Intel processors based on the Core microarchitecture on 26 June 2006 with the "Woodcrest" Xeons.

SSSE3 has been referred to by the codenames Tejas New Instructions (TNI) or Merom New Instructions (MNI) for the first processor designs intended to support it.

Functionality

SSSE3 contains 16 new discrete instructions.

Each instruction can act on 64-bit MMX or 128-bit XMM registers. Therefore, Intel's materials refer to 32 new instructions.

According to Intel:

SSSE3 provide 32 instructions (represented by 14 mnemonics) to accelerate computations on packed integers. These include:

  • Twelve instructions that perform horizontal addition or subtraction operations.
  • Six instructions that evaluate absolute values.
  • Two instructions that perform multiply and add operations and speed up the evaluation of dot products.
  • Two instructions that accelerate packed-integer multiply operations and produce integer values with scaling.
  • Two instructions that perform a byte-wise, in-place shuffle according to the second shuffle control operand.
  • Six instructions that negate packed integers in the destination operand if the signs of the corresponding element in the source operand is less than zero.
  • Two instructions that align data from the composite of two operands.

CPUs with SSSE3

New Instructions

In the table below, satsw(X) (read as 'saturate to signed word') takes a signed integer X, and converts it to −32768 if it's less than −32768, to +32767 if it's greater than 32767, and leaves it unchanged otherwise. As normal for the Intel architecture, bytes are 8 bits, words 16 bits, and dwords 32 bits; 'register' refers to an MMX or XMM vector register.

PSIGNB, PSIGNW, PSIGND Packed Sign Negate the elements of a register of bytes, words or dwords if the sign of the corresponding elements of another register is negative.
PABSB, PABSW, PABSD Packed Absolute Value Fill the elements of a register of bytes, words or dwords with the absolute values of the elements of another register
PALIGNR Packed Align Right take two registers, concatenate their values, and pull out a register-length section from an offset given by an immediate value encoded in the instruction.
PSHUFB Packed Shuffle Bytes takes registers of bytes A = [a0 a1 a2 ...] and B = [b0 b1 b2 ...] and replaces A with [ab0 ab1 ab2 ...]; except that it replaces the ith entry with 0 if the top bit of bi is set.
PMULHRSW Packed Multiply High with Round and Scale treat the sixteen-bit words in registers A and B as signed 15-bit fixed-point numbers between −1 and 1 (e.g. 0x4000 is treated as 0.5 and 0xa000 as −0.75), and multiply them together with correct rounding.
PMADDUBSW Multiply and Add Packed Signed and Unsigned Bytes Take the bytes in registers A and B, multiply them together, add pairs, signed-saturate and store. I.e. [a0 a1 a2 …] pmaddubsw [b0 b1 b2 …] = [satsw(a0b0+a1b1) satsw(a2b2+a3b3) …]
PHSUBW, PHSUBD Packed Horizontal Subtract (Words or Doublewords) takes registers A = [a0 a1 a2 …] and B = [b0 b1 b2 …] and outputs [a0−a1 a2−a3 … b0−b1 b2−b3 …]
PHSUBSW Packed Horizontal Subtract and Saturate Words like PHSUBW, but outputs [satsw(a0−a1) satsw(a2−a3) … satsw(b0−b1) satsw(b2−b3) …]
PHADDW, PHADDD Packed Horizontal Add (Words or Doublewords) takes registers A = [a0 a1 a2 …] and B = [b0 b1 b2 …] and outputs [a0+a1 a2+a3 … b0+b1 b2+b3 …]
PHADDSW Packed Horizontal Add and Saturate Words like PHADDW, but outputs [satsw(a0+a1) satsw(a2+a3) … satsw(b0+b1) satsw(b2+b3) …]

See also

References


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