Experiment with friendlier branch

This commit is contained in:
Justine Tunney 2021-11-27 20:38:00 -08:00
parent 2a00af296b
commit 626f71b9a3
3 changed files with 149 additions and 155 deletions

View file

@ -1,5 +1,4 @@
CFLAGS = -w -Os
LDFLAGS = -s
CFLAGS = -w -g
CLEANFILES = \
lisp \

273
lisp.c
View file

@ -28,121 +28,78 @@
#include <setjmp.h>
#endif
/*───────────────────────────────────────────────────────────────────────────│─╗
The LISP Challenge § LISP Machine
*/
#define kT 4
#define kQuote 6
#define kCond 12
#define kAtom 17
#define kCar 22
#define kCdr 26
#define kCons 30
#define kEq 35
#define M (RAM + sizeof(RAM) / sizeof(RAM[0]) / 2)
#define S "NIL\0T\0QUOTE\0COND\0ATOM\0CAR\0CDR\0CONS\0EQ"
int cx; /* stores negative memory use */
int dx; /* stores lookahead character */
int RAM[0100000]; /* your own ibm7090 */
jmp_buf undefined;
int cx, dx, M[0100000];
int Null = sizeof(M) / sizeof(M[0]) / 2;
char *line = "NIL T CAR CDR ATOM COND CONS QUOTE EQ ";
int kT, kEq, kNil, kCar, kCdr, kCond, kAtom, kCons, kQuote;
Intern() {
int i, j, x;
for (i = 0; (x = M[i++]);) {
for (j = 0;; ++j) {
if (x != RAM[j]) break;
if (!x) return i - j - 1;
x = M[i++];
}
while (x)
x = M[i++];
}
j = 0;
x = --i;
while ((M[i++] = RAM[j++]));
return x;
Get(i) {
return M[Null + i];
}
GetChar() {
int c, t;
static char *l, *p;
if (l || (l = p = bestlineWithHistory("* ", "sectorlisp"))) {
if (*p) {
c = *p++ & 255;
} else {
free(l);
l = p = 0;
c = '\n';
}
t = dx;
dx = c;
return t;
} else {
PrintChar('\n');
exit(0);
}
}
PrintChar(b) {
fputwc(b, stdout);
}
GetToken() {
int c, i = 0;
do if ((c = GetChar()) > ' ') RAM[i++] = c;
while (c <= ' ' || (c > ')' && dx > ')'));
RAM[i] = 0;
return c;
}
AddList(x) {
return Cons(x, GetList());
}
GetList() {
int c = GetToken();
if (c == ')') return 0;
return AddList(GetObject(c));
}
GetObject(c) {
if (c == '(') return GetList();
return Intern();
Set(i, x) {
M[Null + i] = x;
}
Read() {
return GetObject(GetToken());
return ReadObject(ReadAtom(0));
}
Intern(x, y, i) {
if (x == Get(i) && y == Get(i + 1)) return i;
if (Get(i)) return Intern(x, y, i + 2);
Set(i, x);
Set(i + 1, y);
return i;
}
ReadAtom(i) {
int c = ReadChar();
if (c <= ' ') return ReadAtom(i);
return Intern(c, c > ')' && dx > ')' ? ReadAtom(0) : 0, i + c * 2);
}
AddList(x) {
return Cons(x, ReadList());
}
ReadList() {
int t = ReadAtom(0);
if (Get(t) == ')') return kNil;
return AddList(ReadObject(t));
}
ReadObject(t) {
if (Get(t) != '(') return t;
return ReadList();
}
PrintAtom(x) {
int c;
for (;;) {
if (!(c = M[x++])) break;
PrintChar(c);
}
do PrintChar(Get(x));
while ((x = Get(x + 1)));
}
PrintList(x) {
PrintChar('(');
PrintObject(Car(x));
while ((x = Cdr(x))) {
if (x < 0) {
PrintChar(' ');
PrintObject(Car(x));
} else {
PrintChar(L'');
PrintObject(x);
break;
if (x < 0) {
PrintObject(Car(x));
while ((x = Cdr(x)) != kNil) {
if (x < 0) {
PrintChar(' ');
PrintObject(Car(x));
} else {
PrintChar(L'');
PrintObject(x);
break;
}
}
}
PrintChar(')');
}
PrintObject(x) {
if (x < 0) {
if (1./x < 0) {
PrintList(x);
} else {
PrintAtom(x);
@ -154,39 +111,49 @@ Print(e) {
PrintChar('\n');
}
/*───────────────────────────────────────────────────────────────────────────│─╗
The LISP Challenge § Bootstrap John McCarthy's Metacircular Evaluator
*/
Car(x) {
if (x >= 0) longjmp(undefined, x);
return M[x];
if (x < 0) {
return Get(x);
} else {
longjmp(undefined, x);
}
}
Cdr(x) {
if (x >= 0) longjmp(undefined, x);
return M[x + 1];
if (x < 0) {
return Get(x + 1);
} else {
longjmp(undefined, x);
}
}
Cons(car, cdr) {
M[--cx] = cdr;
M[--cx] = car;
Set(--cx, cdr);
Set(--cx, car);
return cx;
}
Gc(x, m, k) {
return x < m ? Cons(Gc(Car(x), m, k),
Gc(Cdr(x), m, k)) + k : x;
Gc(A, x) {
int C, B = cx;
x = Copy(x, A, A - B), C = cx;
while (C < B) Set(--A, Get(--B));
cx = A;
return x;
}
Copy(x, m, k) {
return x < m ? Cons(Copy(Car(x), m, k),
Copy(Cdr(x), m, k)) + k : x;
}
Evlis(m, a) {
return m ? Cons(Eval(Car(m), a),
Evlis(Cdr(m), a)) : 0;
return m != kNil ? Cons(Eval(Car(m), a),
Evlis(Cdr(m), a)) : kNil;
}
Pairlis(x, y, a) {
return x ? Cons(Cons(Car(x), Car(y)),
Pairlis(Cdr(x), Cdr(y), a)) : a;
return x != kNil ? Cons(Cons(Car(x), Car(y)),
Pairlis(Cdr(x), Cdr(y), a)) : a;
}
Assoc(x, y) {
@ -196,63 +163,93 @@ Assoc(x, y) {
}
Evcon(c, a) {
if (Eval(Car(Car(c)), a)) {
if (Eval(Car(Car(c)), a) != kNil) {
return Eval(Car(Cdr(Car(c))), a);
} else {
} else if (Cdr(c) != kNil) {
return Evcon(Cdr(c), a);
} else {
longjmp(undefined, c);
}
}
Apply(f, x, a) {
if (f < 0) return Eval(Car(Cdr(Cdr(f))), Pairlis(Car(Cdr(f)), x, a));
if (f > kEq) return Apply(Eval(f, a), x, a);
if (f == kEq) return Car(x) == Car(Cdr(x)) ? kT : 0;
if (f == kEq) return Car(x) == Car(Cdr(x)) ? kT : kNil;
if (f == kCons) return Cons(Car(x), Car(Cdr(x)));
if (f == kAtom) return Car(x) < 0 ? 0 : kT;
if (f == kAtom) return Car(x) < 0 ? kNil : kT;
if (f == kCar) return Car(Car(x));
if (f == kCdr) return Cdr(Car(x));
longjmp(undefined, f);
return Apply(Assoc(f, a), x, a);
}
Eval(e, a) {
int A, B, C;
if (!e) return 0;
if (e > 0) return Assoc(e, a);
int A = cx;
if (e == kNil) return kNil;
if (e >= 0) return Assoc(e, a);
if (Car(e) == kQuote) return Car(Cdr(e));
A = cx;
if (Car(e) == kCond) {
e = Evcon(Cdr(e), a);
} else {
e = Apply(Car(e), Evlis(Cdr(e), a), a);
}
B = cx;
e = Gc(e, A, A - B);
C = cx;
while (C < B)
M[--A] = M[--B];
cx = A;
return e;
return Gc(A, e);
}
/*───────────────────────────────────────────────────────────────────────────│─╗
The LISP Challenge § User Interface
*/
main() {
int x, a = 0;
int x, a;
setlocale(LC_ALL, "");
bestlineSetXlatCallback(bestlineUppercase);
for(x = 0; x < sizeof(S); ++x) M[x] = S[x];
for (;;) {
kNil = ReadAtom(0);
kT = ReadAtom(0);
kCar = ReadAtom(0);
kCdr = ReadAtom(0);
kAtom = ReadAtom(0);
kCond = ReadAtom(0);
kCons = ReadAtom(0);
kQuote = ReadAtom(0);
kEq = ReadAtom(0);
for (a = kNil;;) {
if (!(x = setjmp(undefined))) {
x = Eval(Read(), a);
x = Read();
x = Eval(x, a);
if (x < 0) {
a = Cons(x, a);
}
} else {
if (x == 1) x = 0;
PrintChar('?');
}
Print(x);
}
}
PrintChar(b) {
fputwc(b, stdout);
}
ReadChar() {
int b, c, t;
static char *freeme;
if (line || (line = freeme = bestlineWithHistory("* ", "sectorlisp"))) {
if (*line) {
c = *line++ & 0377;
if (c >= 0300) {
for (b = 0200; c & b; b >>= 1) c ^= b;
while ((*line & 0300) == 0200) {
c <<= 6;
c |= *line++ & 0177;
}
}
} else {
free(freeme);
freeme = 0;
line = 0;
c = '\n';
}
t = dx;
dx = c;
return t;
} else {
PrintChar('\n');
exit(0);
}
}

View file

@ -23,12 +23,13 @@
// Compatible with the original hardware
.code16
.set save,-10
.set look,start+2
.set save,-2-2
.set look,start+5-2
.globl _start
_start: .asciz "NIL" # dec %si ; dec %cx ; dec %sp
kT: .asciz "T" # add %dl,(%si) boot A:\ DL=0
start: ljmp $0x7c00>>4,$begin # cs = 0x7c00 is boot address
start: mov $0x8000,%sp # this should be safe we hope
ljmp $0x7c00>>4,$begin # cs = 0x7c00 is boot address
.asciz ""
kQuote: .asciz "QUOTE"
kCond: .asciz "COND"
@ -38,20 +39,17 @@ kCdr: .asciz "CDR" # ordering matters
kCons: .asciz "CONS" # ordering matters
kEq: .asciz "EQ" # needs to be last
begin: mov $2,%bx
mov $0x8000,%cx
main: cli
push %cs # that means ss = ds = es = cs
begin: push %cs # that means ss = ds = es = cs
pop %ds # noting ljmp set cs to 0x7c00
push %cs # that's the bios load address
pop %es # therefore NULL points to NUL
push %cs # terminated NIL string above!
pop %ss # errata exists but don't care
xor %sp,%sp # use highest address as stack
sti
call GetToken
mov $2,%bx
mov %sp,%cx
main: call GetToken
call GetObject
mov %dx,save
mov %dx,save(%bx)
call Eval
test %ax,%ax
jns Print
@ -69,7 +67,7 @@ Print: xchg %ax,%si
GetToken: # GetToken():al
mov %cx,%di
1: mov look,%al
1: mov look(%bx),%al
cmp $' ',%al
jbe 2f
stosb
@ -79,12 +77,12 @@ GetToken: # GetToken():al
jne 4f
dec %di
jmp 2b
4: xchg %ax,look
4: xchg %ax,look(%bx)
cmp $' ',%al
jbe 1b
cmp $')',%al
jbe 3f
cmpb $')',look
cmpb $')',look(%bx)
ja 1b
3: mov %bh,(%di) # bh is zero
xchg %si,%ax
@ -147,7 +145,7 @@ Undef: push %ax
mov $'?',%al
call PutChar
pop %ax
mov save,%dx
mov save(%bx),%dx
jmp Print
GetChar:xor %ax,%ax # GetCharal:dl