diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 60 |
1 files changed, 60 insertions, 0 deletions
@@ -54026,6 +54026,16 @@ only \*(TL .code float type. +.ccIP @ bool +The type +.code bool +is a typedef name for the +.code uchar +instance of the parametrized +.code bool +type, which is to say, +.codn "(bool uchar)" . + .ccIP @ val The FFI .code val @@ -54836,6 +54846,56 @@ object. The get semantics retrieves a Lisp value without freeing. +.meIP (bool << type ) +The parametrized type +.code bool +can be derived from any integer or floating-point type. There is also an +unparametrized +.code bool +which is a +.code typedef +for the type +.codn "(bool uchar)" . + +The +.code bool +type family represents Boolean values, converting between a Lisp Boolean +and foreign Boolean. A given instance of the +.code bool +type inherits all of its characteristics from +.metn type , +such as its size, alignment and foreign representation. It alters the +get and put semantics, however. The get semantics converts a foreign zero +value of +.meta type +to the Lisp symbol +.codn nil , +and all other values to the symbol +.codn t . +The put semantics converts the Lisp symbol +.code nil +to a foreign value of zero. Any other Lisp object converts to the foreign +value one. + +The +.code bool +types are not integers, and cannot be used as the basis of bitfields: +syntax like +.code "(bits 3 (bool uint))" +is not permitted. However, Boolean bitfields are possible when this +syntax is turned inside out: the +.code bool +type can be derived from a bitfield type, as exemplified by +.codn "(bool (bits 3 uint))" . +This simply applies the above described Boolean conversion semantics to a +three-bit field. A zero/nonzero value of the field converts to +.cod3 nil / t +and a +.code nil +or +.cod2 non- nil +Lisp value converts to a 0 or 1 field value. + .meIP ({ubit | sbit} << width ) The .code ubit |