several improvements
This commit is contained in:
ceriel
parent
b40425786c
commit
db54c35c24
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@ -736,6 +736,7 @@ interchanged before being processed.
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<num1> gives the number of lines of the first block.
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<num2> gives the number of lines of the second one.
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Blank and pure comment lines do not count.
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This instruction is obsolete. Its use is strongly discouraged.
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.OU
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.sp
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MES <num>,<val>*
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@ -154,7 +154,7 @@ mini with <num> as argument
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mini with <num>*wordsize as argument
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.PE 1
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<num> is a possibly negative integer.
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.VS 1 1
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.VS
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.IE
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The dispatch table for the 256 primary opcodes:
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.N 1
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@ -141,7 +141,7 @@ have been added manually. Note that this code has already been optimized.
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lol 0
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adp 2
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sti 8 ; r.r2 :=
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lni ; lin 23 prior to optimization
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lni ; lin 30 prior to optimization
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lal \-224
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lol \-4
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lae .2
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@ -176,7 +176,7 @@ have been added manually. Note that this code has already been optimized.
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sti 8 ; r2 := x + y
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loc 0
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sil \-226 ; r1 := 0
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lin 34 ; note the abscence of the unnecesary jump
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lin 34 ; note the absence of the unnecessary jump
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lae 22 ; address of output structure
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lol \-4
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cal $_wri ; write integer with default width
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@ -2,7 +2,10 @@
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.AP "EM INTERPRETER"
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.nf
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.ft CW
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.ta 8 16 24 32 40 48 56 64 72 80
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.lg 0
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.nr x \w' '
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.ta \nxu +\nxu +\nxu +\nxu +\nxu +\nxu +\nxu +\nxu +\nxu +\nxu
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.so em.i
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.ft P
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.lg 1
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.fi
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@ -168,7 +168,7 @@ bit pattern:\fBddd\fP:\e\fBddd\fP
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.TE
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.DE
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The escape \fB\eddd\fP consists of the backslash followed by 1,
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2, or 3 octal digits specifing the value of
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2, or 3 octal digits specifying the value of
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the desired character.
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If the character following a backslash is not one of those
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specified,
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@ -206,11 +206,11 @@ l l l.
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.TE
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.IE
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.S3 "Pseudoinstructions"
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.S4 Storage declaration
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.S4 "Storage declaration"
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Initialized global data is allocated by the pseudoinstruction CON,
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which needs at least one argument.
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Each argument is used to allocate and initialize a number of
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consequtive bytes in data memory.
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consecutive bytes in data memory.
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The number of bytes to be allocated and the alignment depend on the type
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of the argument.
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For each argument, an integral number of words,
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@ -257,7 +257,7 @@ Switching to another type of fragment or placing a label forces
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word-alignment.
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There are three types of fragments in global data space: CON, ROM and
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BSS/HOL.
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.N 2
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.N 1
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.IS 2
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.PS - 4
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.PT "BSS <cst1>,<val>,<cst2>"
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@ -277,7 +277,7 @@ Assemble global data words initialized with the <val> constants.
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Idem, but the initialized data will never be changed by the program.
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.PE
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.IE
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.S4 Partitioning
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.S4 "Partitioning"
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Two pseudoinstructions partition the input into procedures:
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.IS 2
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.PS - 4
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@ -295,7 +295,7 @@ The number of bytes for locals must be specified in either the PRO or
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END pseudoinstruction or both.
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.PE
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.IE
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.S4 Visibility
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.S4 "Visibility"
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Names of data and procedures in an EM module can either be
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internal or external.
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External names are known outside the module and are used to link
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@ -329,7 +329,7 @@ Internal procedure.
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<pro> is internal to this module and must be defined in this module.
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.PE
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.IE
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.S4 Miscellaneous
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.S4 "Miscellaneous"
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Two other pseudoinstructions provide miscellaneous features:
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.IS 2
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.PS - 4
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@ -339,6 +339,7 @@ interchanged before being processed.
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<cst1> gives the number of lines of the first block.
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<cst2> gives the number of lines of the second one.
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Blank and pure comment lines do not count.
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This instruction is obsolete. Its use is strongly discouraged.
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.PT "MES <cst>[,<par>]*"
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A special type of comment.
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Used by compilers to communicate with the
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@ -400,7 +401,7 @@ the locals in this procedure should not be kept in registers and
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all registers containing locals of other procedures should be
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saved upon entry to this procedure.
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.PE 1
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.VS 1 1
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.VS
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Each backend is free to skip irrelevant MES pseudos.
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.PE
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.IE
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@ -456,6 +457,7 @@ r l.
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Absence of an optional argument is indicated by a special
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byte.
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.IE 2
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.NE 7
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.CS
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Common Table for Neutral State and Arguments
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.CE
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@ -490,7 +492,7 @@ are presented in two's complement notation, with the least
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significant byte first. For example: the value of a 32 bit
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constant is ((s4*256+b3)*256+b2)*256+b1, where s4 is b4\-256 if
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b4 is greater than 128 else s4 takes the value of b4.
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A <string> consists of a <cst> inmediatly followed by
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A <string> consists of a <cst> immediately followed by
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a sequence of bytes with length <cst>.
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.P
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.ne 8
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@ -588,6 +590,7 @@ Instructions that check for undefined integer or floating-point
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values and underflow or overflow
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are indicated below by (*).
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.N 1
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.VS 0 0
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.DS
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.ta 12n
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GROUP 1 \- LOAD
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@ -799,3 +802,4 @@ GROUP 15 \- MISCELLANEOUS
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STR \*r : Store register (0=LB, 1=SP, 2=HP)
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TRP \*- : Cause trap to occur (Error number on stack)
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.DE 0
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.VS
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@ -18,9 +18,9 @@ Range check descriptors consist of two integers:
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.IS 2
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.PS 1 4 "" .
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.PT
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lower bound~~~~~~~signed
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lower bound signed
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.PT
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upper bound~~~~~~~signed
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upper bound signed
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.PE
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.IE
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The range check instruction checks an integer on the stack against
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@ -34,11 +34,11 @@ Array descriptors contain the following three integers:
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.IS 2
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.PS 1 4 "" .
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.PT
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lower bound~~~~~~~~~~~~~~~~~~~~~signed
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lower bound signed
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.PT
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upper bound \- lower bound~~~~~~~unsigned
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upper bound \- lower bound unsigned
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.PT
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number of bytes per element~~~~~unsigned
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number of bytes per element unsigned
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.PE
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.IE
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The array instructions LAR, SAR and AAR have the pointer to the start
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@ -88,7 +88,7 @@ value of LB after the jump
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.IE
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GTO replaces the loads PC, SP and LB from the descriptor,
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thereby jumping to a procedure
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and removing zeor or more frames from the stack.
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and removing zero or more frames from the stack.
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The LB, SP and PC in the descriptor must belong to a
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dynamically enclosing procedure,
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because some EM implementations will need to backtrack through
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@ -70,7 +70,7 @@ The result of a LFR is only defined if the size used to fetch
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is identical to the size used in the last return.
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The instruction ASP, used to remove the parameters from the
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stack, the branch instruction BRA and the non-local goto
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instrucion GTO are the only ones that leave the contents of
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instruction GTO are the only ones that leave the contents of
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the 'function return area' intact.
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All other instructions are allowed to destroy the function
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return area.
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@ -159,7 +159,7 @@ var
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iclass: insclass; { true for escaped opcodes }
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dispat: array[insclass,byte] of dispatch;
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retsize:size; { holds size of last LFR }
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insr: mnem; { holds the instructionnumber }
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insr: mnem; { holds the instruction number }
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halted: boolean; { normally false }
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exitstatus:word; { parameter of MON 1 }
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ignmask:word; { ignore mask for traps }
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@ -522,7 +522,7 @@ begin j:=0;
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end;
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{---------------------------------------------------------------------------}
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{ Array indexing
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{ Array indexing }
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{---------------------------------------------------------------------------}
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function arraycalc(c:adr):adr; { subscript calculation }
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@ -209,3 +209,4 @@ trap number \-3, the signal is ignored.
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The flag returned by fork is 1 in the child process and 0 in
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the parent.
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The pid returned is the process-id of the other process.
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.VS
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@ -86,7 +86,7 @@
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lol 0
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adp 2
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sti 8 ; r.r2 :=
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lni ; was lin 23 prior to optimization
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lni ; was lin 30 prior to optimization
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lal -224
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lol -4
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lae .2
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@ -121,7 +121,7 @@
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sti 8 ; r2 := x + y
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loc 0
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sil -226 ; r1 := 0
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lin 34 ; note the abscence of the unnecesary jump
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lin 34 ; note the absence of the unnecessary jump
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lae 22 ; address of output structure
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lol -4
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cal $_wri ; write integer with default width
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@ -159,8 +159,11 @@ and not with the symbolic assembly language.
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.P
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As mentioned above, the
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current microcomputer technology offers 8, 16 and 32 bit
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machines with address spaces ranging from 2\v'-0.5m'16\v'0.5m'
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to 2\v'-0.5m'32\v'0.5m' bytes.
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machines with address spaces ranging from
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.Ex 2 16
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to
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.Ex 2 32
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bytes.
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Having one size of pointers and integers restricts
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the usefulness of the language.
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We decided to have a different language for each combination of
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@ -22,19 +22,15 @@ two groups of 256 secondary opcodes each.
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EM instructions without arguments have a single opcode assigned,
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possibly escaped:
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.Dr 6
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|--------------|
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| opcode |
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|--------------|
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.De
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or
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.Dr 6
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|--------------|--------------|
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| escape | opcode |
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|--------------|--------------|
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.De
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The encoding for instructions with an argument is more complex.
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Several instructions have an address from the global data area
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@ -45,37 +41,29 @@ and negative arguments.
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There is always an opcode that takes the next two bytes as argument,
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high byte first:
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.Dr 6
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|--------------|--------------|--------------|
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| opcode | hibyte | lobyte |
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|--------------|--------------|--------------|
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.De
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or
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.Dr 6
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|--------------|--------------|--------------|--------------|
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| escape | opcode | hibyte | lobyte |
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|--------------|--------------|--------------|--------------|
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.De
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An extra escape is provided for instructions with four or eight byte arguments.
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.Dr 6
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|--------------|--------------|--------------| |--------------|
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| ESCAPE | opcode | hibyte |...| lobyte |
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|--------------|--------------|--------------| |--------------|
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.De
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For most instructions some argument values predominate.
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The most frequent combinations of instruction and argument
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will be encoded in a single byte, called a mini:
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.Dr 6
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|---------------|
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|opcode+argument| (mini)
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|---------------|
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.De
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The number of minis is restricted, because only
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254 primary opcodes are available.
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@ -90,19 +78,15 @@ into a single opcode.
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These opcodes are called shorties.
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Shorties may be escaped.
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.Dr 6
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|--------------|--------------|
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| opcode+high | lobyte | (shortie)
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|--------------|--------------|
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.De
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or
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.Dr 6
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|--------------|--------------|--------------|
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| escape | opcode+high | lobyte |
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|--------------|--------------|--------------|
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.De
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Escaped shorties are useless if the normal encoding has a primary opcode.
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Note that for some instruction-argument combinations
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@ -136,7 +120,7 @@ Each descriptor contains:
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the number of bytes to be reserved for locals at each
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invocation.
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.N
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This is a pointer-szied integer.
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This is a pointer-sized integer.
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.PT 2.
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the start address of the procedure
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.PE
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@ -217,6 +201,7 @@ unused
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unused
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.PE
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.IE
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.VS
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.P
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The program text consists of NTEXT bytes.
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NTEXT is always a multiple of the wordsize.
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@ -247,12 +232,12 @@ At load time an interpreter can
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perform any conversion deemed necessary, such as
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reordering bytes in integers
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and pointers and adding base addresses to pointers.
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.BP
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.A
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In the following pictures we show a graphical notation of the
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initializers.
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The leftmost rectangle represents the leading byte.
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.N 1
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.VS 1 0
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.DS
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.PS - 4 " "
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Fields marked with
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@ -271,9 +256,8 @@ contain a data or instruction pointer
|
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contain a null terminated ASCII string
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.PE 1
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.DE 0
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.VS 1 1
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.VS
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.Dr 6
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-------------------
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| 0 | n | repeat last initialization n times
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-------------------
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@ -331,7 +315,7 @@ contain a null terminated ASCII string
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-------------------------
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| 8 | m | s | initialized float of size m
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-------------------------
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.De 3
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.De
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.PS - 8
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.PT type~0:
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If the last initialization initialized k bytes starting
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|
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@ -23,7 +23,7 @@
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..
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.de Df \" Drawing Footer
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.N 1
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.FT P
|
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.ft R
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.CS
|
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.lg 1
|
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..
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@ -33,3 +33,7 @@
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.AD
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.N \\$1
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..
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.\" macro for exponents, added by Ceriel Jacobs
|
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.de Ex \" Exponent $1 $2 [$3]
|
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\\$1\v'-0.5m'\s-2\\$2\s+2\v'0.5m'\\$3
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..
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|
|
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@ -195,7 +195,6 @@ LOI:1:pop:r0:pop:r0
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LOE:40:push:eb+40:push:eb-41
|
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.TE
|
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.DE
|
||||
.BP
|
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.P
|
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The translation for the two implementations, if the target machine address is
|
||||
used as pointer representation, is:
|
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|
|
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@ -1,7 +1,8 @@
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.po 0
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.TP 1
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.ll 79n
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.sp 15
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\&
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.sp 10
|
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.ce 4
|
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DESCRIPTION OF A MACHINE
|
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ARCHITECTURE FOR USE WITH
|
||||
|
|
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|
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@ -8,7 +8,7 @@ This mechanism uses five instructions: LIM, SIM, SIG, TRP and RTT.
|
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This section of the manual may be omitted on the first reading since it
|
||||
presupposes knowledge of the EM instruction set.
|
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.P
|
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The action taken when a trap occures is determined by the value
|
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The action taken when a trap occurs is determined by the value
|
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of an internal EM trap register.
|
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This register contains a pointer to a procedure.
|
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Initially the pointer used is zero and all traps halt the
|
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|
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@ -124,7 +124,7 @@ ersave
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msave
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bss 2,0,0 ; Room to save previous value of trap mask
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|
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pro calcule,0 ; entry point
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pro $calcule,0 ; entry point
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lxl 0 ; fill in non-local goto descriptor with LB
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ste jmpbuf+4
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lor 1 ; and SP
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@ -151,11 +151,11 @@ jmpbuf
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con *1,0,0
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end
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.DE 0
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.VS 1 1
|
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.VS
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.DS
|
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Example of catch procedure
|
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.ta 1n 24n
|
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pro catch,0 ; Local procedure that must catch the overflow trap
|
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pro $catch,0 ; Local procedure that must catch the overflow trap
|
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lol 2 ; Load trap number
|
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loc 4 ; check for overflow
|
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bne *1 ; if other trap, call higher trap procedure
|
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|
|
|
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|
|
@ -33,7 +33,8 @@ restrictions imposed on the representation of the types used.
|
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A number \fBn\fP used in these paragraphs indicates the size of
|
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the object in \fIbits\fP.
|
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.S2 "Unsigned integers"
|
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The range of unsigned integers is 0..2\v'-0.5m'\fBn\fP\v'0.5m'\-1.
|
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The range of unsigned integers is 0..
|
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.Ex 2 "\fBn\fP" -1.
|
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A binary representation is assumed.
|
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The order of the bits within an object is knowingly left
|
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unspecified.
|
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|
|
@ -61,17 +62,23 @@ We assume existence of at least single word unsigned arithmetic
|
|||
in any implementation.
|
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.S2 "Signed Integers"
|
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The range of signed integers is
|
||||
\-2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP\-1\v'0.5m'\-1,
|
||||
.Ex \-2 "\fBn\fP\-1" ~..
|
||||
.Ex 2 "\fBn\fP\-1" \-1,
|
||||
in other words the range of signed integers of \fBn\fP bits
|
||||
using two's complement arithmetic.
|
||||
The representation is the same as for unsigned integers except the range
|
||||
2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~2\v'-0.5m'\fBn\fP\v'0.5m'\-1 is mapped on the
|
||||
range \-2\v'-0.5m'\fBn\fP\-1\v'0.5m'~..~\-1.
|
||||
.Ex 2 "\fBn\fP\-1" ~..
|
||||
.Ex 2 "\fBn\fP" \-1
|
||||
is mapped on the
|
||||
range
|
||||
.Ex \-2 "\fBn\fP\-1" ~..~\-1.
|
||||
In other words, the most significant bit is used as sign bit.
|
||||
The convert instructions between signed and unsigned integers
|
||||
of the same size can be used to catch errors.
|
||||
.A
|
||||
The value \-2\v'-0.5m'\fBn\fP\-1\v'0.5m' is used for undefined
|
||||
The value
|
||||
.Ex \-2 "\fBn\fP\-1"
|
||||
is used for undefined
|
||||
signed integers.
|
||||
EM implementations should trap when this value is used in an
|
||||
operation on signed integers.
|
||||
|
|
@ -80,7 +87,6 @@ can be used to disable such traps.
|
|||
.A
|
||||
We assume existence of at least single word signed arithmetic
|
||||
in any implementation.
|
||||
.BP
|
||||
.S2 "Floating point values"
|
||||
Floating point values must have a signed mantissa and a signed
|
||||
exponent.
|
||||
|
|
|
|||
Loading…
Reference in a new issue