vec_lvsl

Purpose

Returns a vector useful for aligning non-aligned data.

Syntax

d=vec_lvsl(a, b)

Result and argument types

The following table describes the types of the returned value and the function arguments.

Result value

The result value is a quad vector. The elements of the quad vector are generated in the following ways:

• Sign: 0
• Mantissa:
  1. For the first element, the mantissa is the result of following operations:
     • If b is a pointer to a double-precision floating-point value or complex value:
       1. Add a and b.
       2. Mask the result of the previous step with 0b11000.
       3. Take the integer value of bits 58 - 60 from the result of the previous step.
     • If b is a pointer to a single-precision floating-point value or complex value:
       1. Add a and b.
       2. Multiply the result of the previous step by two.
       3. Mask the result of the previous step with 0b11000.
       4. Take the integer value of bits 58 - 60 from the result of the previous step.
  2. The mantissa is incremented by one for each subsequent element.

     The mantissa is seen as a 3-bit value for the increment operation. That is, incrementing 0b111 produces 0b000.

• Exponent: 0x400

You can use the result as an argument of the vec_perm function.

Formula

The following formula is applicable if b is a pointer to a double-precision floating-point value or complex value:

EA = a + b
AA = EA AND 0b11000
Offset = AA58:60
d[0] = (double) {sign = 0, mantissa =  Offset             , exponent = 0x400}
d[1] = (double) {sign = 0, mantissa = (Offset+1) AND 0b111, exponent = 0x400}
d[2] = (double) {sign = 0, mantissa = (Offset+2) AND 0b111, exponent = 0x400}
d[3] = (double) {sign = 0, mantissa = (Offset+3) AND 0b111, exponent = 0x400}

The following formula is applicable if b is a pointer to a single-precision floating-point value or complex value:

EA = a + b
AA = (EA × 2) AND 0b11000
Offset = AA58:60
d[0] = (double) {sign = 0, mantissa =  Offset             , exponent = 0x400}
d[1] = (double) {sign = 0, mantissa = (Offset+1) AND 0b111, exponent = 0x400}
d[2] = (double) {sign = 0, mantissa = (Offset+2) AND 0b111, exponent = 0x400}
d[3] = (double) {sign = 0, mantissa = (Offset+3) AND 0b111, exponent = 0x400}