;;;; This file contains some parameterizations of various VM
;;;; attributes for the x86. This file is separate from other stuff so
;;;; that it can be compiled and loaded earlier.
;;;; 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.
;;; ### Note: we simultaneously use ``word'' to mean a 32 bit quantity
;;; and a 16 bit quantity depending on context. This is because Intel
;;; insists on calling 16 bit things words and 32 bit things
;;; double-words (or dwords). Therefore, in the instruction definition
;;; and register specs, we use the Intel convention. But whenever we
;;; are talking about stuff the rest of the lisp system might be
;;; interested in, we use ``word'' to mean the size of a descriptor
;;; object, which is 32 bits.
;;;; machine architecture parameters
;;; the number of bits per word, where a word holds one lisp descriptor
(def!constant n-word-bits 32)
;;; the number of bits per byte, where a byte is the smallest
;;; addressable object
(def!constant n-byte-bits 8)
;;; the number of bits to shift between word addresses and byte addresses
(def!constant word-shift (1- (integer-length (/ n-word-bits n-byte-bits))))
;;; the number of bytes in a word
(def!constant n-word-bytes (/ n-word-bits n-byte-bits))
(def!constant float-sign-shift 31)
;;; comment from CMU CL:
;;; These values were taken from the alpha code. The values for
;;; bias and exponent min/max are not the same as shown in the 486 book.
;;; They may be correct for how Python uses them.
(def!constant single-float-bias 126) ; Intel says 127.
(defconstant-eqx single-float-exponent-byte (byte 8 23) #'equalp)
(defconstant-eqx single-float-significand-byte (byte 23 0) #'equalp)
;;; comment from CMU CL:
;;; The 486 book shows the exponent range -126 to +127. The Lisp
;;; code that uses these values seems to want already biased numbers.
(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 long-float-bias 16382)
(defconstant-eqx long-float-exponent-byte (byte 15 0) #'equalp)
(defconstant-eqx long-float-significand-byte (byte 31 0) #'equalp)
(def!constant long-float-normal-exponent-min 1)
(def!constant long-float-normal-exponent-max #x7FFE)
(def!constant long-float-hidden-bit (ash 1 31)) ; actually not hidden
(def!constant long-float-trapping-nan-bit (ash 1 30))
(+ (byte-size single-float-significand-byte) 1))
(+ (byte-size double-float-significand-byte) n-word-bits 1))
(+ (byte-size long-float-significand-byte) n-word-bits 1))
;;; pfw -- from i486 microprocessor programmer's reference manual
(def!constant float-invalid-trap-bit (ash 1 0))
(def!constant float-denormal-trap-bit (ash 1 1))
(def!constant float-divide-by-zero-trap-bit (ash 1 2))
(def!constant float-overflow-trap-bit (ash 1 3))
(def!constant float-underflow-trap-bit (ash 1 4))
(def!constant float-inexact-trap-bit (ash 1 5))
(def!constant float-round-to-nearest 0)
(def!constant float-round-to-negative 1)
(def!constant float-round-to-positive 2)
(def!constant float-round-to-zero 3)
(defconstant-eqx float-rounding-mode (byte 2 10) #'equalp)
(defconstant-eqx float-sticky-bits (byte 6 16) #'equalp)
(defconstant-eqx float-traps-byte (byte 6 0) #'equalp)
(defconstant-eqx float-exceptions-byte (byte 6 16) #'equalp)
(defconstant-eqx float-precision-control (byte 2 8) #'equalp)
(def!constant float-fast-bit 0) ; no fast mode on x86
;;;; description of the target address space
;;; where to put the different spaces
;;; Note: Mostly these values are black magic, inherited from CMU CL
;;; without any documentation. However, there were a few explanatory
;;; comments in the CMU CL sources:
;;; * On Linux,
;;; ** The space 0x08000000-0x10000000 is "C program and memory allocation".
;;; ** The space 0x40000000-0x48000000 is reserved for shared libs.
;;; ** The space >0xE0000000 is "C stack - Alien stack".
;;; * On FreeBSD,
;;; ** The space 0x0E000000-0x10000000 is "Foreign segment".
;;; ** The space 0x20000000-0x30000000 is reserved for shared libs.
;;; And there have been some changes since the fork from CMU CL:
;;; * The OpenBSD port is new since the fork. We started with
;;; the FreeBSD address map, which actually worked until the
;;; Alpha port patches, for reasons which in retrospect are rather
;;; mysterious. After the Alpha port patches were added, the
;;; OpenBSD port suffered memory corruption problems. While
;;; debugging those, it was discovered that src/runtime/trymap
;;; failed for the control stack region #x40000000-#x47fff000.
;;; After the control stack was moved upward out of this region
;;; (stealing some bytes from dynamic space) the problems went
;;; * The FreeBSD STATIC-SPACE-START value was bumped up from
;;; #x28000000 to #x30000000 when FreeBSD ld.so dynamic linking
;;; support was added for FreeBSD ca. 20000910. This was to keep from
;;; stomping on an address range that the dynamic libraries want to
;;; use. (They want to use this address range even if we try to
;;; reserve it with a call to validate() as the first operation in
(def!constant read-only-space-start #x01000000)
(def!constant read-only-space-end #x037ff000)
(def!constant static-space-start #x05000000)
(def!constant static-space-end #x07fff000)
(def!constant dynamic-space-start #x09000000)
(def!constant dynamic-space-end #x29000000)
(def!constant alternate-signal-stack-start #x58000000))
(def!constant read-only-space-start #x10000000)
(def!constant read-only-space-end #x1ffff000)
(def!constant static-space-end #x37fff000)
(def!constant dynamic-space-end #x88000000)
;;; don't need alternate-signal-stack-end : it's -start+SIGSTKSZ
;;; Given that NIL is the first thing allocated in static space, we
;;; know its value at compile time:
(def!constant nil-value (+ static-space-start #xb))
;;;; other miscellaneous constants
(defenum (:suffix -trap :start 8)
;;; FIXME: It'd be nice to replace all the DEFENUMs with something like
;;; (WITH-DEF-ENUM (:START 8)
;;; (DEF-ENUM HALT-TRAP)
;;; (DEF-ENUM PENDING-INTERRUPT-TRAP)
;;; for the benefit of anyone doing a lexical search for definitions
;;; of these symbols.
(defenum (:prefix object-not- :suffix -trap :start 16)
(defenum (:prefix trace-table-)
;;;; 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.
;;; pfw X86 doesn't have enough registers to keep these things there.
;;; Note these spaces grow from low to high addresses.
;;; FIXME: !COLD-INIT probably doesn't need
;;; to be in the static symbols table any more.
;; The C startup code must fill these in.
;; functions that the C code needs to call. When adding to this list,
;; also add a `frob' form in genesis.lisp finish-symbols.
;; free pointers
;; Note that these are FIXNUM word counts, not (as one might
;; expect) byte counts or SAPs. The reason seems to be that by
;; representing them this way, we can avoid consing bignums.
;; -- WHN 2000-10-02
;; things needed for non-local exit
;; interrupt handling
;; the floating point constants
;; The following are all long-floats.
;; The ..SLOT-UNBOUND.. symbol is static in order to optimise the
;; common slot unbound check.
;; FIXME: In SBCL, the CLOS code has become sufficiently tightly
;; integrated into the system that it'd probably make sense to use
;; the ordinary unbound marker for this.
;;;; stuff added by jrd
;;; FIXME: Is this used? Delete it or document it.
;;; cf the sparc PARMS.LISP
(defparameter *assembly-unit-length* 8)