From 74151efc043c984ae328be599417570a8b75ff0f Mon Sep 17 00:00:00 2001 From: "Kartik K. Agaram" Date: Sat, 15 May 2021 19:49:52 -0700 Subject: reimplement Bresenham line in Mu --- 506math.mu | 21 +++++++++++++++++++++ 507line.mu | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 83 insertions(+) create mode 100644 506math.mu create mode 100644 507line.mu diff --git a/506math.mu b/506math.mu new file mode 100644 index 00000000..d4e4194c --- /dev/null +++ b/506math.mu @@ -0,0 +1,21 @@ +fn abs n: int -> _/eax: int { + compare n, 0 + { + break-if->= + negate n + } + return n +} + +fn sgn n: int -> _/eax: int { + compare n, 0 + { + break-if-<= + return 1 + } + { + break-if->= + return -1 + } + return 0 +} diff --git a/507line.mu b/507line.mu new file mode 100644 index 00000000..7afdf9cc --- /dev/null +++ b/507line.mu @@ -0,0 +1,62 @@ +fn draw-line screen: (addr screen), x0: int, y0: int, x1: int, y1: int, color: int { + var dx: int + var dy: int + var sx: int + var sy: int + var err: int + # dx = abs(x1-x0) + var tmp2/ecx: int <- copy x1 + tmp2 <- subtract x0 + var tmp/eax: int <- abs tmp2 + copy-to dx, tmp + # sx = sgn(x1-x0) + tmp <- sgn tmp2 + copy-to sx, tmp + # dy = -abs(y1-y0) + tmp2 <- copy y1 + tmp2 <- subtract y0 + tmp <- abs tmp2 + tmp <- negate + copy-to dy, tmp + # sy = sgn(y1-y0) + tmp <- sgn tmp2 + copy-to sy, tmp + # err = dx + dy + tmp <- copy dy + tmp <- add dx + copy-to err, tmp + # + var x/ecx: int <- copy x0 + var y/edx: int <- copy y0 + $draw-line:loop: { + pixel screen, x, y, color + # if (x == x1 && y == y1) break + { + compare x, x1 + break-if-!= + compare y, y1 + break-if-!= + break $draw-line:loop + } + # e2 = err*2 + var e2/ebx: int <- copy err + e2 <- shift-left 1 + # if (e2 >= dy) { err += dy; x += sx; } + { + compare e2, dy + break-if-< + tmp <- copy dy + add-to err, tmp + x <- add sx + } + # if (e2 <= dx) { err += dx; y += sy; } + { + compare e2, dx + break-if-> + tmp <- copy dx + add-to err, tmp + y <- add sy + } + loop + } +} -- cgit 1.4.1-2-gfad0 e='author'>author
path: root/106stream.subx
blob: 9949ee7d3b906753e7553013f7b42a77508c60e2 (plain) (blame) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

# streams: data structure for operating on arrays in a stateful manner
#
# A stream looks like this:
#   write: int  # index at which writes go
#   read: int  # index that we've read until
#   data: (array byte)  # prefixed by size as usual
#
# some primitives for operating on streams:
#   - clear-stream (clears everything but the data size)
#   - rewind-stream (resets read pointer)
#
# We need to do this in machine code because streams need to be opaque types,
# and we don't yet support opaque types in Mu.

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

clear-stream:  # f: (addr stream byte)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    51/push-ecx
    # eax = f
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
    # var count/ecx: int = f->size
    8b/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           1/r32/ecx   8/disp8         .                 # copy *(eax+8) to ecx
    # var max/ecx: (addr byte) = &f->data[f->size]
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   0xc/disp8       .                 # copy eax+ecx+12 to ecx
    # f->write = 0
    c7          0/subop/copy        0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm32           # copy to *eax
    # f->read = 0
    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         0/imm32           # copy to *(eax+4)
    # - clear all stream data
    # - this isn't strictly necessary, and it can slow things down *a lot*, but better safe than sorry.
    # var curr/eax: (addr byte) = f->data
    81          0/subop/add         3/mod/direct    0/rm32/eax    .           .             .           .           .               0xc/imm32         # add to eax
$clear-stream:loop:
    # if (curr >= max) break
    39/compare                      3/mod/direct    0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # compare eax with ecx
    73/jump-if-addr>=  $clear-stream:end/disp8
    # *curr = 0
    c6          0/subop/copy-byte   0/mod/direct    0/rm32/eax    .           .             .           .           .               0/imm8            # copy byte to *eax
    # ++curr
    40/increment-eax
    eb/jump  $clear-stream:loop/disp8
$clear-stream:end:
    # . restore registers
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

rewind-stream:  # f: (addr stream byte)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    50/push-eax
    # eax = f
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
    # f->read = 0
    c7          0/subop/copy        1/mod/*+disp8   0/rm32/eax    .           .             .           .           4/disp8         0/imm32           # copy to *(eax+4)
$rewind-stream:end:
    # . restore registers
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# . . vim:nowrap:textwidth=0