Merge pull request #1 from peterferrie/master

shave some bytes

ray.asm

@@ -31,23 +31,25 @@ com_file: equ 0
 
  %if com_file
  org 0x0100 ; Start address for COM file
+ mov al,0x13 ; Video mode 320x200x256 colors
  %else
  org 0x7c00 ; Start address for boot sector
+ mov ax,0x0013 ; Video mode 320x200x256 colors
  %endif
 
- mov ax,0x0013 ; Video mode 320x200x256 colors
  int 0x10 ; Call BIOS.
 
- sub sp,total ; Make space for internal variables.
- mov bp,sp ; Use BP to refer them.
+ enter total-2,0 ; Make space for internal variables,
+  ; and use BP to refer them.
 
- mov ax,0xa000 ; Point to video RAM.
- mov es,ax
+ push 0xa000 ; Point to video RAM.
+ pop es
 
- finit ; Reset coprocessor.
+ fninit ; Reset coprocessor.
  cld ; Clear direction flag.
+ mov si, const_2
 restart:
- fld dword [const_25] ; Initial viewpoint (z)
+ fld dword [si+const_25-const_2] ; Initial viewpoint (z)
  fstp dword [bp+var_a] ; a = 25.0
 e0:
  xor di,di ; Pixel pointer.
@@ -62,13 +64,13 @@ e2:
  fst dword [bp+var_z]
 
  fsubp ; y = -a / 25
- fdiv dword [const_25]
+ fdiv dword [si+const_25-const_2]
  fstp dword [bp+var_y]
 
  fld1
 
  fild word [bp+var_m] ; The X-coordinate defines the current sphere.
- fsub dword [const_80_5]
+ fsub dword [si+const_80_5-const_2]
  fldz
  fcomip
  fld1 ; One sphere at 1.
@@ -78,13 +80,13 @@ e2:
 e3:
  fstp dword [bp+var_i]
 
- fdiv dword [const_80_1_3]
+ fdiv dword [si+const_80_1_3-const_2]
  fst dword [bp+var_u] ; X-direction of ray.
  fmul st0
 
  fild word [bp+var_n]
- fsub dword [const_80_5]
- fdiv dword [const_80_1_3]
+ fsub dword [si+const_80_5-const_2]
+ fdiv dword [si+const_80_1_3-const_2]
  fst dword [bp+var_v] ; Y-direction of ray.
  fmul st0
 
@@ -159,7 +161,7 @@ e4:
 
  call sphere
 
- fmul dword [const_2]
+ fmul dword [si]
  fst dword [bp+var_p]
 
  fmul dword [bp+var_e] ; Update ray direction.
@@ -190,7 +192,7 @@ e5:
  jbe e6
  fstp st0
  fld dword [bp+var_y]
- fadd dword [const_2]
+ fadd dword [si]
  fdiv dword [bp+var_v]
  fst dword [bp+var_p] ; Perspective correction.
 
@@ -204,20 +206,20 @@ e5:
  faddp
  fst dword [bp+var_s]
 
- fdiv dword [const_2] ; Modulus 2.
+ fdiv dword [si] ; Modulus 2.
  frndint
- fmul dword [const_2]
+ fmul dword [si]
  fsubr dword [bp+var_s]
 
- fdiv dword [const_2] ; Modulate final result.
- fadd dword [const__3]
+ fdiv dword [si] ; Modulate final result.
+ fadd dword [si+const__3-const_2]
  fldz
  fsub dword [bp+var_v]
  fmulp
- fadd dword [const_1_4] ; Color offset for floor.
+ fadd dword [si+const_1_4-const_2] ; Color offset for floor.
 e6:
  fsqrt ; Make a curved gradient (like inside of a sphere)
- fmul dword [const_25] ; Spread over 25 pixel values.
+ fmul dword [si+const_25-const_2] ; Spread over 25 pixel values.
  fistp word [bp+pixel] ; Convert to integer.
 
 ; mov ax,199 ; Not necessary as DI contains the pixel pointer.
@@ -237,9 +239,9 @@ e6:
  jns e1 ; Continue if it is still positive.
 
  fld dword [bp+var_a] ; Move viewing point.
- fsub dword [const___1]
+ fsub dword [si+const___1-const_2]
  fst dword [bp+var_a]
- fadd dword [const_2]
+ fadd dword [si]
  fldz
  fcomip ; Reached the limit?
  fstp st0