Ssse3 Instruction Set

Here we will briefly describe several important arithmetic operation commands.

1. Horizontal addition command

The ssse3 Instruction Set adds commands that add integers horizontally, similar to the floating point commands of sse3.

Phaddd

Add a 32-bit unsigned integer in the horizontal direction of the Register

 

Phaddw

Add the registers horizontally according to the unsigned 16-bit integer

 

Phaddsw

Registers are saturated based on 16-digit integers in the horizontal direction.

Phsubd

The registers are subtracted horizontally by unsigned 32-bit integers.

 

Phsubw

The registers are subtracted horizontally by unsigned 16-bit integers.

 

Phsubsw

Perform saturation subtraction based on 16-digit integers in the horizontal direction of registers

Example:

PhaddwDeST, SRC

Add and package the source and target data horizontally, applicable to MMX and SSE registers:
Dest [] includest [31: 16] + Dest [];
Dest [31: 16] includest [63: 48] + Dest [47: 32];
Dest [47: 32] parse SRC [31: 16] + SRC [];
Dest [63: 48]Using SRC [63: 48] + SRC [47: 32];
The XMM registers are similar.

2. Saturated byte multiplication and addition command

Pmaddubsw

Perform multiplication based on the location of the byte. When the adjacent two numbers are added, the 16-bit signed number is saturated.

Example:Pmaddubsw DEST, SRC

 

Obtains the signed saturation value of the multiplication of the source and target data. It is applicable to MMX and SSE registers:
Dest [] ← saturatetosword (SRC [] * DST [] + SRC [] * DST []);
Dest [31: 16] ← saturatetosword (SRC [31: 24] * DST [31: 24] + SRC [23:16] * DST [23:16]);
Dest [47: 32] ← saturatetosword (SRC [47: 40] * DST [47: 40] + SRC [39: 32] * DST [39: 32]);
Dest [63: 48] ← saturatetosword (SRC [63: 56] * DST [63: 56] + SRC [55: 48] * DST [55: 48]);
The XMM registers are similar.

 

3. Use 16-bit multiplication to obtain a high value

Pmulhrsw

This command is specially designed for fixed-point operations.

 

Use pseudoCodeThe description is more convenient:

 

 Signed   Short A [  8  ]  ;   // Input  Signed   Short B [  8  ]  ;  // Input B  Signed   Short R [  8  ]  ;   // Output R  For   ( I =  0  ; I <   8  ; I ++  ) R [ I ]  = Int16 (  ( A [ I ]  * B [ I ]   +   Zero X 4000  )   >   15  )  ; 

 

 This is a rounding shift operation in q15 fixed-point format,It is quite common in speech signal processing.

 

4. Absolute Value operation

Pabsb/pabsw/pabsd

 

Example:Pabsw

 

Take the absolute value of the source data, applicable to MMX and SSE registers:
Dest [] Reverse ABS (SRC []);
Dest [31: 16] Reverse ABS (SRC [31: 16]);
Dest [47: 32] Reverse ABS (SRC [47: 32]);
Dest [63: 48] Reverse ABS (SRC [63: 48]);
The XMM registers are similar.

5. byte mixed selection command

Pshufb

This command is flexible and used to select any byte of the source register and re-arrange it to the destination register.

 

The pseudocode is described as follows:

 Char A [  16  ] ;   // Input  Char B [  16  ]  ;   // Input B  Char R [  16  ]  ;   // Output R  For   ( I =  0  ; I <  16  ; I ++  ) R [ I ]   =   ( B [ I ]   <   0  )   ?   0   : A [ B [ I ]   %   16 ]  ;


If the high sign bit of the source operand is 1, that is, when the source operand is smaller than zero, the destination register is assigned to zero.
Otherwise, select the destination operand based on the lower 4 bits of the source operand and copy it to the corresponding bits of the destination operand.