"Processor SIMD units supported by the " { $vocab-link "math.vectors.simd" } " vocabulary represent boolean values as bitmasks, where a true result's binary representation is all ones and a false representation is all zeroes. This is the format in which results from comparison words such as " { $link v= } " return their results and in which logic and test words such as " { $link vand } " and " { $link vall? } " take their inputs when working with SIMD types. For a float vector, false will manifest itself as " { $snippet "0.0" } " and true as a " { $link POSTPONE: NAN: } " literal with a string of set bits in its payload:"
{ $example
"""USING: math.vectors math.vectors.simd prettyprint ;
-FROM: alien.c-types => float ;
-SIMD: float
float-4{ 1.0 2.0 3.0 0/0. } float-4{ 1.0 -2.0 3.0 0/0. } v= ."""
"""float-4{ NAN: fffffe0000000 0.0 NAN: fffffe0000000 0.0 }"""
"For an integer vector, false will manifest as " { $snippet "0" } " and true as " { $snippet "-1" } " (for signed vectors) or the largest representable value of the element type (for unsigned vectors):"
{ $example
"""USING: math.vectors math.vectors.simd prettyprint alien.c-types ;
-SIMD: int
-SIMD: uchar
int-4{ 1 2 3 0 } int-4{ 1 -2 3 4 } v=
uchar-16{ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 }
"This differs from Factor's native representation of boolean values, where " { $link f } " is false and every other value (including " { $snippet "0" } " and " { $snippet "0.0" } ") is true. To make it easy to construct literal SIMD masks, " { $link t } " and " { $link f } " are accepted inside SIMD literal syntax and expand to the proper true or false representation for the underlying type:"
{ $example
"""USING: math.vectors math.vectors.simd prettyprint alien.c-types ;
-SIMD: int
int-4{ f f t f } ."""
"""int-4{ 0 0 -1 0 }""" }
$nl
"Providing a SIMD boolean vector with element values other than the proper true and false representations as an input to the vector logical or test operations is undefined. Do not count on operations such as " { $link vall? } " or " { $link v? } " using bitwise operations to construct their results."
$nl
-"This applies to the output of the following element comparison words: "
+"This applies to the output of the following element comparison words:"
{ $list
{ $link v< }
{ $link v<= }
{ $description "Truncates each element of " { $snippet "u" } "." } ;
HELP: n+v
-{ $values { "n" "a number" } { "u" "a sequence of numbers" } { "v" "a sequence of numbers" } }
+{ $values { "n" "a number" } { "v" "a sequence of numbers" } { "w" "a sequence of numbers" } }
{ $description "Adds " { $snippet "n" } " to each element of " { $snippet "u" } "." } ;
HELP: v+n
-{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "v" "a sequence of numbers" } }
+{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "w" "a sequence of numbers" } }
{ $description "Adds " { $snippet "n" } " to each element of " { $snippet "u" } "." } ;
HELP: n-v
-{ $values { "n" "a number" } { "u" "a sequence of numbers" } { "v" "a sequence of numbers" } }
+{ $values { "n" "a number" } { "v" "a sequence of numbers" } { "w" "a sequence of numbers" } }
{ $description "Subtracts each element of " { $snippet "u" } " from " { $snippet "n" } "." } ;
HELP: v-n
-{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "v" "a sequence of numbers" } }
+{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "w" "a sequence of numbers" } }
{ $description "Subtracts " { $snippet "n" } " from each element of " { $snippet "u" } "." } ;
HELP: n*v
-{ $values { "n" "a number" } { "u" "a sequence of numbers" } { "v" "a sequence of numbers" } }
+{ $values { "n" "a number" } { "v" "a sequence of numbers" } { "w" "a sequence of numbers" } }
{ $description "Multiplies each element of " { $snippet "u" } " by " { $snippet "n" } "." } ;
HELP: v*n
-{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "v" "a sequence of numbers" } }
+{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "w" "a sequence of numbers" } }
{ $description "Multiplies each element of " { $snippet "u" } " by " { $snippet "n" } "." } ;
HELP: n/v
-{ $values { "n" "a number" } { "u" "a sequence of numbers" } { "v" "a sequence of numbers" } }
+{ $values { "n" "a number" } { "v" "a sequence of numbers" } { "w" "a sequence of numbers" } }
{ $description "Divides " { $snippet "n" } " by each element of " { $snippet "u" } "." }
{ $errors "May throw an error if a division by zero occurs; see " { $link "division-by-zero" } "." } ;
HELP: v/n
-{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "v" "a sequence of numbers" } }
+{ $values { "u" "a sequence of numbers" } { "n" "a number" } { "w" "a sequence of numbers" } }
{ $description "Divides each element of " { $snippet "u" } " by " { $snippet "n" } "." }
{ $errors "May throw an error if a division by zero occurs; see " { $link "division-by-zero" } "." } ;
HELP: v+-
{ $values { "u" "a sequence of numbers" } { "v" "a sequence of numbers" } { "w" "a sequence of numbers" } }
-{ $description "Adds and subtracts alternate elements of " { $snippet "v" } " and " { $snippet "u" } " component-wise." }
+{ $description "Adds and subtracts alternate elements of " { $snippet "v" } " and " { $snippet "u" } " component-wise. Elements at even indexes are subtracted, while elements at odd indexes are added." }
{ $examples
{ $example
"USING: math.vectors prettyprint ;"
{ $examples
{ $example
"USING: alien.c-types math.vectors math.vectors.simd" "prettyprint ;"
- "SIMD: int"
"int-4{ 69 42 911 13 } 2 vbroadcast ."
"int-4{ 911 911 911 911 }"
}
{ $examples
{ $example
"USING: alien.c-types math.vectors math.vectors.simd" "prettyprint ;"
- "SIMD: int"
"int-4{ 69 42 911 13 } { 1 3 2 3 } vshuffle ."
"int-4{ 42 13 911 13 }"
}
" { 4 [ uchar-16{ 3 2 1 0 7 6 5 4 11 10 9 8 15 14 13 12 } ] }"
" } case ;"
""
- "int-4{ HEX: 11223344 HEX: 11223344 HEX: 11223344 HEX: 11223344 }"
+ "int-4{ 0x11223344 0x11223344 0x11223344 0x11223344 }"
"4 endian-swap vshuffle"
"16 number-base [ . ] with-variable"
"""int-4{
- HEX: 44332211
- HEX: 44332211
- HEX: 44332211
- HEX: 44332211
+ 0x44332211
+ 0x44332211
+ 0x44332211
+ 0x44332211
}"""
}
} ;
projects / factor.git / blobdiff