;;;; This software is part of the SBCL system. See the README file for ;;;; more information. ;;;; ;;;; This software is derived from the CMU CL system, which was ;;;; written at Carnegie Mellon University and released into the ;;;; public domain. The software is in the public domain and is ;;;; provided with absolutely no warranty. See the COPYING and CREDITS ;;;; files for more information. (in-package "SB!VM") (eval-when (:compile-toplevel :load-toplevel :execute) ;;; number of bits per word where a word holds one lisp descriptor (def!constant n-word-bits 32) ;;; the natural width of a machine word (as seen in e.g. register width, ;;; address space) (def!constant n-machine-word-bits 64) ;;; number of bits per byte where a byte is the smallest addressable ;;; object (def!constant n-byte-bits 8) (def!constant float-sign-shift 31) (def!constant single-float-bias 126) (defconstant-eqx single-float-exponent-byte (byte 8 23) #'equalp) (defconstant-eqx single-float-significand-byte (byte 23 0) #'equalp) (def!constant single-float-normal-exponent-min 1) (def!constant single-float-normal-exponent-max 254) (def!constant single-float-hidden-bit (ash 1 23)) (def!constant single-float-trapping-nan-bit (ash 1 22)) (def!constant double-float-bias 1022) (defconstant-eqx double-float-exponent-byte (byte 11 20) #'equalp) (defconstant-eqx double-float-significand-byte (byte 20 0) #'equalp) (def!constant double-float-normal-exponent-min 1) (def!constant double-float-normal-exponent-max #x7FE) (def!constant double-float-hidden-bit (ash 1 20)) (def!constant double-float-trapping-nan-bit (ash 1 19)) (def!constant single-float-digits (+ (byte-size single-float-significand-byte) 1)) (def!constant double-float-digits (+ (byte-size double-float-significand-byte) n-word-bits 1)) ;;; These values are originally from the DEC Assembly Language ;;; Programmers guide. Where possible we read/write the software ;;; fp_control word, which apparently is necessary for the OS FPU ;;; completion (OS handler which fixes up non-IEEE answers that the ;;; hardware occasionally gives us) to work properly. The rounding ;;; mode, however, can't be set that way, so we have to deal with that ;;; directly. (FIXME: we actually don't suport setting the rounding mode ;;; at the moment anyway) ;;; Short guide to floating point trap terminology: an "exception" is ;;; cheap and can happen at almost any time. An exception will only ;;; generate a trap if that trap is enabled, otherwise a default value ;;; will be substituted. A "trap" will end up somewhere in the ;;; kernel, which may play by its own rules, (on Alpha it allegedly ;;; actually fixes up some non-IEEE compliant results to get the ;;; _right_ answer) but if something is really wrong will eventually ;;; signal SIGFPE and let us sort it out. ;;; Old comment follows: The active bits are actually in (byte 12 52) ;;; of the fpcr. (byte 6 52) contain the exception flags. Bit 63 is the ;;; bitwise logor of all exceptions. The enable and exception bytes ;;; are in a software control word manipulated via OS functions and the ;;; bits in the SCP match those defs. This mapping follows ;;; ;;; trap enables are set in software (fp_control) (def!constant float-inexact-trap-bit (ash 1 4)) ; rw (def!constant float-underflow-trap-bit (ash 1 3)) ; rw (def!constant float-overflow-trap-bit (ash 1 2)) ; ro (def!constant float-divide-by-zero-trap-bit (ash 1 1)) ; ro (def!constant float-invalid-trap-bit (ash 1 0)) ; ro (defconstant-eqx float-traps-byte (byte 6 1) #'equalp) ;;; exceptions are also read/written in software (by syscalls, no less). ;;; This is kind of dumb, but has to be done (defconstant-eqx float-sticky-bits (byte 6 17) #'equalp) ; fp_control ;;; (We don't actually _have_ "current exceptions" on Alpha; the ;;; hardware only ever sets bits. So, set this the same as accrued ;;; exceptions) (defconstant-eqx float-exceptions-byte (byte 6 17) #'equalp) ;;; Rounding modes can only be set by frobbing the hardware fpcr directly (def!constant float-round-to-zero 0) (def!constant float-round-to-negative 1) (def!constant float-round-to-nearest 2) (def!constant float-round-to-positive 3) (defconstant-eqx float-rounding-mode (byte 2 58) #'equalp) ;;; Miscellaneous stuff - I think it's far to say that you deserve ;;; what you get if you ask for fast mode. (def!constant float-fast-bit 0) ); eval-when ;;;; Description of the target address space. ;;; Where to put the different spaces. ;;; #!+linux (progn (def!constant read-only-space-start #x20000000) (def!constant read-only-space-end #x24000000)) #!+osf1 (progn (defconstant read-only-space-start #x10000000) (defconstant read-only-space-end #x25000000)) (def!constant static-space-start #x28000000) (def!constant static-space-end #x2c000000) (def!constant dynamic-0-space-start #x30000000) (def!constant dynamic-0-space-end #x3fff0000) (def!constant dynamic-1-space-start #x40000000) (def!constant dynamic-1-space-end #x4fff0000) ;;; FIXME nothing refers to either of these in alpha or x86 cmucl ;;; backend, so they could probably be removed. ;; The space-register holding the lisp heap. (def!constant lisp-heap-space 4) ;; The space-register holding the C text segment. (def!constant c-text-space 4) ;;; the X86 port defines *nil-value* as (+ *target-static-space-start* #xB) ;;; here, but it seems to be the only port that needs to know the ;;; location of NIL from lisp. ;;;; other miscellaneous constants (defenum (:suffix -trap :start 8) halt pending-interrupt error cerror breakpoint fun-end-breakpoint single-step-breakpoint) (defenum (:prefix trace-table-) normal call-site fun-prologue fun-epilogue) ;;;; static symbols ;;; These symbols are loaded into static space directly after NIL so ;;; that the system can compute their address by adding a constant ;;; amount to NIL. ;;; ;;; The fdefn objects for the static functions are loaded into static ;;; space directly after the static symbols. That way, the raw-addr ;;; can be loaded directly out of them by indirecting relative to NIL. ;;; (defparameter *static-symbols* '(t ;; The C startup code must fill these in. *posix-argv* ;; functions that the C code needs to call sub-gc sb!kernel::internal-error sb!kernel::control-stack-exhausted-error sb!kernel::undefined-alien-variable-error sb!kernel::undefined-alien-function-error sb!di::handle-breakpoint sb!di::handle-fun-end-breakpoint ;; free pointers *read-only-space-free-pointer* *static-space-free-pointer* *initial-dynamic-space-free-pointer* ;; things needed for non-local exit *current-catch-block* *current-unwind-protect-block* *binding-stack-start* *control-stack-start* *control-stack-end* ;; interrupt handling *free-interrupt-context-index* sb!unix::*interrupts-enabled* sb!unix::*interrupt-pending*)) (defparameter *static-funs* '(length sb!kernel:two-arg-+ sb!kernel:two-arg-- sb!kernel:two-arg-* sb!kernel:two-arg-/ sb!kernel:two-arg-< sb!kernel:two-arg-> sb!kernel:two-arg-= ;; FIXME: Is this ;; probably need the following as they are defined in ;; arith.lisp: two-arg-<= two-arg->= two-arg-/= ;; a comment from old CMU CL or old old CMU CL or ;; the SBCL alpha port or what? Do we need to worry about it, ;; or can we delete it? sb!kernel:two-arg-/= eql sb!kernel:%negate sb!kernel:two-arg-and sb!kernel:two-arg-ior sb!kernel:two-arg-xor sb!kernel:two-arg-eqv sb!kernel:two-arg-gcd sb!kernel:two-arg-lcm))