;;; -*-scheme-*-

(define (int->bv32 value)
  (let ((bv (make-bytevector 4)))
    (bytevector-u32-native-set! bv 0 value)
    bv))

(define (int->bv16 value)
  (let ((bv (make-bytevector 2)))
    (bytevector-u16-native-set! bv 0 value)
    bv))

(define vaddress #x08048000)

(define ei-magic `(#x7f ,@(string->list "ELF")))
(define ei-class '(#x01)) ;; 32 bit
(define ei-data '(#x01)) ;; little endian
(define ei-version '(#x01))
(define ei-osabi '(#x00))
(define ei-pad '(#x0 #x0 #x0 #x0 #x0 #x0 #x0 #x0))
(define e-ident
  (append
   ei-magic
   ei-class
   ei-data
   ei-version
   ei-osabi
   ei-pad))

(define e-type '(#x02 #x00)) ;; ET_EXEC
(define e-machine '(#x03 #x00))
(define e-version '(#x01 #x00 #x00 #x00))
(define e-entry '(0 0 0 0))
(define e-phoff '(0 0 0 0))
(define e-shoff '(0 0 0 0))
(define e-flags '(#x00 #x00 #x00 #x00))
(define e-ehsize '(0 0))
(define e-phentsize '(0 0))
(define e-phnum '(#x01 #x00))
(define e-shentsize '(0 0))
(define e-shnum '(#x05 #x00))
(define e-shstrndx '(#x04 #x00))

(define (elf-header)
  (append
   e-ident
   e-type
   e-machine
   e-version
   e-entry
   e-phoff
   e-shoff
   e-flags
   e-ehsize
   e-phentsize
   e-phnum
   e-shentsize
   e-shnum
   e-shstrndx
   ))

(define p-type '(#x01 #x00 #x00 #x00))
(define p-offset '(0 0 0 0))
(define p-vaddr '(0 0 0 0))
(define p-paddr '(0 0 0 0))
(define p-filesz '(0 0 0 0))
(define p-memsz '(0 0 0 0))
(define p-flags '(#x07 #x00 #x00 #x00))
(define p-align '(#x01 #x00 #x00 #x00))

(define (program-header-0)
  (append
   p-type
   p-offset
   p-vaddr
   p-paddr
   p-filesz
   p-memsz
   p-flags
   p-align
   ))

(set! e-phentsize (int->bv16 (length (program-header-0))))

(define (program-headers)
  (append
   (program-header-0)
   ))

(define (headers)
  (append
   (elf-header)
   (program-headers)
   ))

(define (elf-header-size)
  (length
   (elf-header)))

(set! e-phoff (int->bv32 (elf-header-size)))
(set! e-ehsize (int->bv16 (elf-header-size)))

(define (text-offset)
  (length (headers)))

(define (i386:puts data)
  `(
    #xba #x0e #x00 #x00 #x00       ;; mov    $0xe,%edx
    #xb9 ,@(int->bv32 data)        ;; mov    $data,%ecx
    #xbb #x01 #x00 #x00 #x00       ;; mov    $0x1,%ebx
    #xb8 #x04 #x00 #x00 #x00       ;; mov    $0x4,%eax
    #xcd #x80                      ;; int    $0x80
  ))

(define (i386:exit code)
  `(
    #xbb ,@(int->bv32 code)        ;; mov    $code,%ebx
    #xb8 #x01 #x00 #x00 #x00       ;; mov    $0x1,%eax
    #xcd #x80                      ;; int    $0x80
    ))

(define (text data)
  (append
   (i386:puts data)
   (i386:exit 0)
   ))

(define (text-length)
  (length (text 0)))

(define (data-offset)
  (length
   (append
    (headers)
    (text 0))))

(define (data-address) (+ (data-offset) vaddress))

(set! p-filesz (int->bv32 (text-length)))
(set! p-memsz (int->bv32 (text-length)))

;; 1076
(define data
  (string->list "Hello, world!\n"))

(define note
  (string->list
   (string-append
    "MES"
    ;;"Mes -- Maxwell Equations of Software\n"
    ;;"https://gitlab.com/janneke/mes"
    )
    ;; #x05 #x00 #x00 #x00 #x00 #x00 #x00 #x00 #x02 #x00 #x00 #x00
    ;; #\i #\3 #\8 #\6 #x00 #x00 #x00 #x00
    ))

;; 1098 sh str table
(define tab
  `(
    #x00 ,@(string->list ".shstrtab")
         #x00 ,@(string->list ".text")
         #x00 ,@(string->list ".data")
         #x00 ,@(string->list ".note")
         #x00 #x00 #x00 #x00
    ))

(define sh-0-name      '(#x99 #x99 #x00 #x00))
(define sh-0-type      '(#x00 #x00 #x00 #x00))
(define sh-0-flags     '(#x00 #x00 #x00 #x00))
(define sh-0-addr      '(#x00 #x00 #x00 #x00))
(define sh-0-offset    '(#x00 #x00 #x00 #x00))
(define sh-0-size      '(#x00 #x00 #x00 #x00))
(define sh-0-link      '(#x00 #x00 #x00 #x00))
(define sh-0-info      '(#x00 #x00 #x00 #x00))
(define sh-0-addralign '(#x00 #x00 #x00 #x00))
(define sh-0-entsize   '(#x00 #x00 #x00 #x00))

(define (sh-0)
  (append
   sh-0-name
   sh-0-type
   sh-0-flags
   sh-0-addr
   sh-0-offset
   sh-0-size
   sh-0-link
   sh-0-info
   sh-0-addralign
   sh-0-entsize
   ))

(set! e-shentsize (int->bv16 (length (sh-0))))

;; 10e0 sh1: .text
(define sh-text-name      '(#x0b #x00 #x00 #x00))
(define sh-text-type      '(#x01 #x00 #x00 #x00))
(define sh-text-flags     '(#x06 #x00 #x00 #x00))
(define sh-text-addr      (int->bv32 (+ vaddress (text-offset))))
(set! e-entry sh-text-addr)
(set! p-vaddr sh-text-addr)
(set! p-paddr sh-text-addr)
(define sh-text-offset    (int->bv32 (text-offset)))
(set! p-offset sh-text-offset)
(define sh-text-size      (int->bv32 (length text)))
(define sh-text-link      '(#x00 #x00 #x00 #x00))
(define sh-text-info      '(#x00 #x00 #x00 #x00))
(define sh-text-addralign '(#x01 #x00 #x00 #x00))
(define sh-text-entsize   '(#x00 #x00 #x00 #x00))

(define (sh-text)
  (append
   sh-text-name
   sh-text-type
   sh-text-flags
   sh-text-addr
   sh-text-offset
   sh-text-size
   sh-text-link
   sh-text-info
   sh-text-addralign
   sh-text-entsize
   ))

;; 1108 sh2: .data
(define sh-data-name      '(#x11 #x00 #x00 #x00))
(define sh-data-type      '(#x01 #x00 #x00 #x00))
(define sh-data-flags     '(#x03 #x00 #x00 #x00))
(define sh-data-addr      (int->bv32 (data-address)))
(define sh-data-offset    (int->bv32 (data-offset)))
(define sh-data-size      (int->bv32 (length data)))
(define sh-data-link      '(#x00 #x00 #x00 #x00))
(define sh-data-info      '(#x00 #x00 #x00 #x00))
(define sh-data-addralign '(#x01 #x00 #x00 #x00))
(define sh-data-entsize   '(#x00 #x00 #x00 #x00))

(define (sh-data)
  (append
   sh-data-name
   sh-data-type
   sh-data-flags
   sh-data-addr
   sh-data-offset
   sh-data-size
   sh-data-link
   sh-data-info
   sh-data-addralign
   sh-data-entsize
   ))

;; 1130 sh3: .note
(define sh-note-name      '(#x17 #x00 #x00 #x00))
(define sh-note-type      '(#x07 #x00 #x00 #x00))
(define sh-note-flags     '(#x00 #x00 #x00 #x00))
(define sh-note-addr      '(#x00 #x00 #x00 #x00))
(define sh-note-offset    '(0 0 0 0))
(define sh-note-size      (int->bv32 (length note)))
(define sh-note-link      '(#x00 #x00 #x00 #x00))
(define sh-note-info      '(#x00 #x00 #x00 #x00))
(define sh-note-addralign '(#x01 #x00 #x00 #x00))
(define sh-note-entsize   '(#x00 #x00 #x00 #x00))

(define (sh-note)
  (append
   sh-note-name
   sh-note-type
   sh-note-flags
   sh-note-addr
   sh-note-offset
   sh-note-size
   sh-note-link
   sh-note-info
   sh-note-addralign
   sh-note-entsize
   ))

;; 1158 sh4: .shstrtab
(define sh-tab-name      '(#x01 #x00 #x00 #x00))
(define sh-tab-type      '(#x03 #x00 #x00 #x00))
(define sh-tab-flags     '(#x00 #x00 #x00 #x00))
(define sh-tab-addr      '(#x00 #x00 #x00 #x00))
(define sh-tab-offset    '(0 0 0 0))
(define sh-tab-size      (int->bv32 (length tab)))
(define sh-tab-link      '(#x00 #x00 #x00 #x00))
(define sh-tab-info      '(#x00 #x00 #x00 #x00))
(define sh-tab-addralign '(#x01 #x00 #x00 #x00))
(define sh-tab-entsize   '(#x00 #x00 #x00 #x00))

(define (sh-tab)
  (append
   sh-tab-name
   sh-tab-type
   sh-tab-flags
   sh-tab-addr
   sh-tab-offset
   sh-tab-size
   sh-tab-link
   sh-tab-info
   sh-tab-addralign
   sh-tab-entsize
   ))

(define (section-headers)
  (append
   (sh-0)
   (sh-text)
   (sh-data)
   (sh-note)
   (sh-tab)
   ))

(define (note-offset)
  (length
   (append
    (headers)
    (text 0)
    data
    )))

(set! sh-note-offset (int->bv32 (note-offset)))

(define (tab-offset)
  (length
   (append
    (headers)
    (text 0)
    data
    note
    )))

(set! sh-tab-offset (int->bv32 (tab-offset)))

(define (section-headers-offset)
  (length
   (append
    (headers)
    (text 0)
    data
    note
    tab)))

(set! e-shoff (int->bv32 (section-headers-offset)))

(define exe
  (append
   (headers)
   (text (data-address))
   data
   note
   tab
   (section-headers)
   ))
(map write-char exe)