Update

Author: INIT-REF

078.asm

@@ -3,33 +3,57 @@ format ELF64 executable 9
 segment readable writable
  result: times 20 db 0 ;empty string for printing the result later
  db 10, 0
- p: rd 101
+ p: rd 100000
 
 segment readable executable
  entry start
 
 start:
- mov dword [p], 1 ;set p[0] to 1
+ mov dword [p], 1 ;p[0] = 1
  xor edi, edi ;init n
 
-sum_outer:
+next_n:
  inc edi ;n++
- mov esi, edi ;m = n 
-
-sum_inner:
- push rsi
- sub esi, edi ;m - n
- mov eax, [p + 4 * esi] ;p[m - n]
- pop rsi
- add [p + 4 * esi], eax ;p[m] += p[m - n]
- inc esi ;m++
- cmp esi, 100 ;end of p?
- jle sum_inner ;if not, continue inner loop
- cmp edi, 99
- jl sum_outer
+ xor esi, esi ;init m
+ mov ebx, 1 ;init gpn(n) (generalized pentagonal number)
+
+p_loop:
+ mov eax, [p + 4 * edi] ;p[n]
+ mov ecx, edi
+ sub ecx, ebx ;n - gpn(m)
+ mov ebx, [p + 4 * ecx] ;p[n - gpn(m)]
+ test esi, 2 ;m mod 4 > 1?
+ jz continue ;if not, jump to continue
+ neg ebx ;else negate ebx
+
+continue:
+ add eax, ebx ;p[n] +/- p[n - gpn(m)]
+ mov ebx, 1000000
+ cdq
+ idiv ebx
+ mov [p + 4 * edi], edx ;result mod 1e6 in p[n]
+ inc esi ;m++
+ mov eax, esi ;get new gpn(m):
+ shr eax, 1
+ inc eax ;k = (m / 2) + 1
+ mov ebx, eax
+ imul ebx, ebx
+ imul ebx, 3 ;3 * k * k
+ test esi, 1 ;m even?
+ jnz odd ;if not, jump to odd
+ neg eax ;if yes, negate eax
+
+odd:
+ add ebx, eax
+ shr ebx, 1 ;gpn(m) = ((3 * k * k) +/- k) / 2
+ cmp ebx, edi
+ jle p_loop
+ mov eax, [p + 4 * edi] ;p[n] = 0 (i. e. p[n] was divisible by 1e6)?
+ test eax, eax
+ jnz next_n ;if not, continue with next n
 
 finished:
- mov eax, [p + 400] ;result in p[100]
+ mov eax, edi
  mov ebx, 10
  mov ecx, 19