sinxor.asm

; (C) October 16, 2001  M. Feliks

include sys.inc

.model tiny
.code
.386

org 100h


entrypoint:

    call    do_startup

      ; set texture
    mov     di, offset texture
    xor     dx, dx
st_ver:
    xor     cx, cx
st_hor:
    mov     ax, cx
    xor     ax, dx
    stosb
    inc     cx
    cmp     cx, 128
    jne     st_hor
    inc     dx
    cmp     dx, 128
    jne     st_ver

      ; calculate palette
    mov     di, offset palette
    xor     ax, ax
    mov     cx, 256
sp_loop:
    stosb
    stosb
    stosb
    inc     ah
    mov     al, ah
    shr     al, 2
    dec     cx
    jnz     sp_loop

      ; init sine wave
    mov     di, offset sinwave
    mov     cx, 256
isv_loop:
    fld     angle
    fld     st
    fsin
    fmul    mul_wave
    fistp   word ptr [di]
    fadd    d_angle
    fstp    angle
    add     di, 2
    dec     cx
    jnz     isv_loop

    mov     si, offset palette
    call    set_palette

main_loop:

      ; fill screen
    push    es
    mov     es, buffer_seg
    xor     di, di

    mov     dx, 200
    mov     bp, sin_pos
dp_ver:
    mov     cx, 320
    mov     si, sin_pos
dp_hor:
    mov     ax, word ptr sinwave[bp]
    add     ax, cx
    and     ax, 127

    mov     bx, word ptr sinwave[si]
    add     bx, dx
    and     bx, 127

    shl     bx, 7
    add     bx, ax
    mov     al, byte ptr texture[bx]
    stosb

    add     si, 2
    and     si, 511

    dec     cx
    jnz     dp_hor

    add     bp, 2
    and     bp, 511

    dec     dx
    jnz     dp_ver
    pop     es

      ; update sine position
    add     sin_pos, 2
    and     sin_pos, 511

    call    timer_wait
    call    copy_buffer

    mov     ah, 6h
    mov     dl, 0ffh
    int     21h
    jz      main_loop

    call    do_shutdown

.data

d_angle dd 0.024543693  ; pi/128
angle dd 0.0
mul_wave dd 12.0

sin_pos dw 0

.data?

texture db 128*128 dup(?)
palette db 768 dup(?)

sinwave dw 256 dup(?)

end entrypoint