mirror of
https://github.com/samsonjs/sectorlisp.git
synced 2026-03-25 09:05:48 +00:00
318 lines
7.5 KiB
ArmAsm
318 lines
7.5 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ Copyright 2021 Alain Greppin │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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// LISP meta-circular evaluator in a MBR
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.set NIL, 1
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.set ATOM_T, 9
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.set ATOM_QUOTE, 13
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.set ATOM_COND, 25
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.set ATOM_ATOM, 35
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.set ATOM_CAR, 45
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.set ATOM_CDR, 53
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.set ATOM_CONS, 61
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.set ATOM_EQ, 71
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.set g_token, 0x7600
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.set g_str, 0x0
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.set g_mem, 0x3600
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.set boot, 0x7c00
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////////////////////////////////////////////////////////////////////////////////
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.section .text,"ax",@progbits
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.globl _start
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.code16
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_start: jmp .init # some bios scan for short jump
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.type kSymbols,@object;
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kSymbols:
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.ascii "NIL\0T\0QUOTE\0COND\0ATOM\0CAR\0CDR\0CONS\0EQ"
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.type .init,@function
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.init: ljmp $0x800>>4,$_begin # end of bios data roundup page
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_begin: push %cs # memory model cs=ds=es = 0x800
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push %cs
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push %cs
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pop %ds
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pop %es
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mov $kSymbols,%si
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mov %si,%cx
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pop %ss
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mov %cx,%sp
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cld
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mov $g_mem,%ax
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mov %ax,%fs # fs = &g_mem
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xor %di,%di
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rep stosb # clears our bss memory
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main: xor %di,%di # mov g_str, %di
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mov $37,%cl
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rep movsb
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0: mov $'\n',%dl
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call GetToken
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call GetObject
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mov $NIL,%dx
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call Eval
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call PrintObject
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mov $'\r',%al
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call PutChar
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jmp 0b
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GetToken: # GetToken():al, dl is g_look
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mov $g_token,%di
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mov %di,%si
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1: mov %dl,%al
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cmp $' ',%al
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jbe 2f
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stosb
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xchg %ax,%cx
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2: call GetChar # bh = 0 after PutChar
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xchg %ax,%dx # dl = g_look
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cmp $' ',%al
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jbe 1b
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cmp $')',%al
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jbe 3f
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cmp $')',%dl
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ja 1b
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3: movb %bh,(%di)
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xchg %cx,%ax
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ret
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.PutObject: # .PutObject(c:al,x:di)
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call PutChar # preserves di
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xchg %di,%ax
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# jmp PrintObject
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PrintObject: # PrintObject(x:ax)
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test $1,%al
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xchg %ax,%di
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jz .PrintList
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.PrintAtom:
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shr %di
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mov %di,%si # lea g_str(%di),%si
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.PrintString: # nul-terminated in si
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lodsb
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test %al,%al
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jz .ret # -> ret
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call PutChar
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jmp .PrintString
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.PrintList:
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mov $'(',%al
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2: push 2(%di) # save 1 Cdr(x)
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mov (%di),%di # di = Car(x)
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call .PutObject
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pop %ax # restore 1
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cmp $NIL,%ax
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je 4f
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test $1,%al
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xchg %ax,%di
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mov $' ',%al
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jz 2b
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mov $249,%al # bullet (A∙B)
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call .PutObject
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4: mov $')',%al
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jmp PutChar
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GetObject: # called just after GetToken
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cmpb $'(',%al
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je GetList
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.Intern:
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xor %di,%di # mov $g_str,%di
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xor %al,%al
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0: push %di # save 1
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1: cmpsb
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jne 2f
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dec %di
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scasb
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jne 1b
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jmp 5f
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2: pop %si # drop 1
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mov $g_token,%si
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3: scasb
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jne 3b
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cmp (%di),%al
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jne 0b
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push %di # StpCpy
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4: movsb
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dec %di
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scasb
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jnz 4b
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5: pop %ax # restore 1
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# add $-g_str,%ax
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add %ax,%ax # ax = 2 * ax
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inc %ax # + 1
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.ret: ret
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GetChar:
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xor %ax,%ax # get keystroke
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int $0x16 # keyboard service
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# ah is bios scancode
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# al is ascii character
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PutChar:
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# push %bx # don't clobber di,si,cx,dx
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# push %bp # original ibm pc scroll up bug
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xor %bx,%bx # normal mda/cga style page zero
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mov $0x0e,%ah # teletype output al cp437
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int $0x10 # vidya service
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# pop %bp # preserves al
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# pop %bx
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cmp $'\r',%al # don't clobber stuff
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jne .ret
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mov $'\n',%al
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jmp PutChar # bx volatile, bp never used
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////////////////////////////////////////////////////////////////////////////////
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Pairlis:cmp $NIL,%di # Pairlis(x:di,y:si,a:dx):ax
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je 1f
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push 2(%di) # save 1 Cdr(x)
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lodsw
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push (%si) # save 2 Cdr(y)
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mov (%di),%di
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xchg %ax,%si
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call Cons # preserves dx
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pop %si # restore 2
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pop %di # restore 1
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push %ax # save 3
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call Pairlis
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xchg %ax,%si
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pop %di # restore 3
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jmp Cons # can be inlined here
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1: xchg %dx,%ax
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ret
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Evlis: cmp $NIL,%di # Evlis(m:di,a:dx):ax
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je 1f
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push 2(%di) # save 1 Cdr(m)
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mov (%di),%ax
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push %dx # save a
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call Eval
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pop %dx # restore a
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pop %di # restore 1
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push %ax # save 2
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call Evlis
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xCons: xchg %ax,%si
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pop %di # restore 2
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# jmp Cons
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Cons: xchg %di,%ax
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mov %fs,%di
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stosw
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xchg %si,%ax
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stosw
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xchg %di,%ax
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mov %fs,%di
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mov %ax,%fs
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1: xchg %di,%ax
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ret
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GetList:call GetToken
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cmpb $')',%al
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je .retF
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call GetObject
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push %ax # save 1
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call GetList
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jmp xCons
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1: mov 2(%di),%di # di = Cdr(c)
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Evcon: push %di # save c
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mov (%di),%di # di = Car(c)
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mov (%di),%ax # ax = Caar(c)
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push %dx # save a
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call Eval
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pop %dx # restore a
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pop %di # restore c
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cmp $NIL,%ax
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jz 1b
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mov (%di),%di # di = Car(c)
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.EvCadr:call Cadr # ax = Cadar(c)
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# jmp Eval
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Eval: test $1,%al # Eval(e:ax,a:dx):ax
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jnz Assoc
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xchg %ax,%di # di = e
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mov (%di),%ax # ax = Car(e)
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cmp $ATOM_QUOTE,%ax # maybe CONS
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mov 2(%di),%di # di = Cdr(e)
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je .retA
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cmp $ATOM_COND,%ax
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je Evcon
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.Ldflt2:push %ax # save 2
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call Evlis # preserves dx
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xchg %ax,%si
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pop %ax # restore 2
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# jmp Apply
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Apply: test $1,%al # Apply(fn:ax,x:si:a:dx):ax
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jnz .switch
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xchg %ax,%di # di = fn
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.lambda:mov 2(%di),%di # di = Cdr(fn)
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push %di # save 1
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mov (%di),%di # di = Cadr(fn)
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call Pairlis
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xchg %ax,%dx
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pop %di # restore 1
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jmp .EvCadr
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.ifCons:mov 2(%si),%si # si = Cdr(x)
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mov (%si),%si # si = Cadr(x)
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cmp $ATOM_CONS,%al
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je Cons
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.isEq: cmp %di,%si
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jne .retF
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.retT: mov $ATOM_T,%al # ax = ATOM_T
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ret
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.switch:cmp $ATOM_EQ,%ax
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ja .dflt1
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mov (%si),%di # di = Car(x)
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.ifCar: cmp $ATOM_CAR,%al
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je .retA
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.ifCdr: cmp $ATOM_CDR,%al
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cmove 2(%di),%ax
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je .retD
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.ifAtom:cmp $ATOM_ATOM,%al
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jne .ifCons
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test $1,%di
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jnz .retT
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.retF: mov $NIL,%ax # ax = NIL
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.retD: ret
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.dflt1: push %si # save x
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push %dx # save a
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call Eval
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pop %dx # restore a
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pop %si # restore x
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jmp Apply
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Cadr: mov 2(%di),%di # contents of decrement register
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.retA: mov (%di),%ax # contents of address register
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ret
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1: mov 2(%si),%dx # dx = Cdr(y)
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Assoc: cmp $NIL,%dx # Assoc(x:ax,y:dx):ax
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mov %dx,%si
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je .retF
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mov (%si),%bx # bx = Car(y)
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cmp %ax,(%bx) # (%bx) = Caar(y)
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jne 1b
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mov 2(%bx),%ax # ax = Cdar(y)
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ret
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.type .sig,@object;
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.sig:
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.fill 510 - (. - _start), 1, 0xce
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.word 0xAA55
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