mandel.s

@@ -16,13 +16,6 @@ dist  = $9c     ; fixed6.26: z_x^2 + z_y^2
 iter  = $a0     ; u8: iteration count
 zoom  = $a1     ; u8: zoom shift level
 temp  = $a2     ; u16
-temp2 = $a4     ; u16
-
-pixel_ptr    = $b0 ; u16
-pixel_color  = $b2 ; u8
-pixel_mask   = $b3 ; u8
-pixel_shift  = $b4 ; u8
-pixel_offset = $b5 ; u8
 
 ; FP registers in zero page
 FR0 = $d4
@@ -40,8 +33,7 @@ framebuffer_end    = $a000
 height = 184
 half_height = height >> 1
 width = 160
-half_width = width >> 1
-stride = width >> 2
+half_width = 160 >> 1
 width_ratio_3_13 = (5 << 11) ; 5/4
 height_ratio_3_13 = (3 << 11) ; 5/4
 
@@ -114,8 +106,8 @@ bit_masks:
     .byte 3 << 6
 
 display_list_start:
-    ; 24 lines overscan
-    .repeat 3
+    ; 48 lines overscan
+    .repeat 5
         .byte $70 ; 8 blank lines
     .endrep
 
@@ -141,14 +133,6 @@ display_list_start:
 display_list_end:
 display_list_len = display_list_end - display_list_start
 
-color_map:
-    .byte 0
-    .repeat 85
-        .byte 1
-        .byte 2
-        .byte 3
-    .endrepeat
-
 .code
 
 .export start
@@ -191,8 +175,8 @@ color_map:
 
 .macro shl bytes, arg
     asl arg
-    .repeat bytes-1, i
-        rol arg + 1 + i
+    .repeat bytes-1
+        rol arg
     .endrepeat
 .endmacro
 
@@ -244,21 +228,6 @@ color_map:
     neg 4, arg
 .endmacro
 
-.macro extend_8_16 dest, src
-    ; clobbers A, X
-    ; 13-15 cycles
-    .local positive
-    .local negative
-    ldx #0       ; 2 cyc
-    lda src      ; 3 cyc
-    sta dest     ; 3 cyc
-    bpl positive ; 2 cyc
-negative:
-    dex          ; 2 cyc
-positive:
-    stx dest + 1 ; 3 cyc
-.endmacro
-
 ; inner loop for imul16
 ; bitnum < 8: 25 or 41 cycles
 ; bitnum >= 8: 30 or 46 cycles
@@ -530,86 +499,6 @@ enough:
     ; screen coords in signed sx,sy
     ; iter holds the target to use
     ; @todo implement
-
-    ; iter -> color
-    ldx iter
-    lda color_map,x
-    sta pixel_color
-    lda #(255 - 3)
-    sta pixel_mask
-
-    ; sy -> line base address in temp
-    lda sy
-    bpl positive
-
-negative:
-    ; temp1 = top half
-    lda #.lobyte(framebuffer_top + stride * half_height)
-    sta pixel_ptr
-    lda #.hibyte(framebuffer_top + stride * half_height)
-    sta pixel_ptr + 1
-    jmp point
-
-positive:
-
-    lda #.lobyte(framebuffer_bottom)
-    sta pixel_ptr
-    lda #.hibyte(framebuffer_bottom)
-    sta pixel_ptr + 1
-
-point:
-
-    ; pixel_ptr += sy * stride
-    ;    temp * 40
-    ; =  temp * 32  +  temp * 8
-    ; = (temp << 5) + (temp << 3)
-    copy16 temp, sy
-    shl16 temp
-    shl16 temp
-    shl16 temp
-    add16 pixel_ptr, pixel_ptr, temp
-    shl16 temp
-    shl16 temp
-    add16 pixel_ptr, pixel_ptr, temp
-
-    ; Ok so temp1 points to the start of the line, which is 40 bytes.
-    ; Get the byte and bit offsets
-    lda sx
-    clc
-    adc #half_width
-    sta temp
-
-    ; pixel_shift = temp & 3
-    ; pixel_color <<= pixel_shift (shifting in zeros)
-    ; pixel_mask <<= pixel_shift (shifting in ones)
-    and #3
-    sta pixel_shift
-    tax
-shift_loop:
-    beq shift_done
-    asl pixel_color
-    asl pixel_color
-    sec
-    rol pixel_mask
-    sec
-    rol pixel_mask
-    dex
-    jmp shift_loop
-shift_done:
-
-    ; pixel_offset = temp >> 2
-    lda temp
-    lsr a
-    lsr a
-    sta pixel_offset
-    tay
-
-    ; read, mask, or, write
-    lda (pixel_ptr),y
-    and pixel_mask
-    ora pixel_color
-    sta (pixel_ptr),y
-
     rts
 .endproc
 
@@ -707,32 +596,33 @@ loop_sx:
     jsr mandelbrot
     jsr pset
 
-    clc
+
     lda sx
+    clc
     adc #1
     sta sx
+
+    cmp #half_width
+    beq loop_sx_done
+
     lda sx + 1
     adc #0
     sta sx + 1
-
-    lda sx
-    cmp #half_width
-    beq loop_sx_done
     jmp loop_sx
 
 loop_sx_done:
 
-    clc
     lda sy
+    clc
     adc #1
     sta sy
+
+    cmp #half_height
+    beq loop_sy_done
+
     lda sy + 1
     adc #0
     sta sy + 1
-
-    lda sy
-    cmp #half_height
-    beq loop_sy_done
     jmp loop_sy
 
 loop_sy_done: