feat: add description-width config option

Descriptions and values are drawn as a single line that never wraps.
Because a diagram is scaled to fit the width it is rendered into, the
longest label is what decides that scale: one long description makes the
whole diagram -- bit cells, indices and every other label with it --
shrink until that line fits. A register whose fields carry a sentence
each is then unreadable at any page width, and since each diagram is
measured on its own, a document full of them renders every one at a
different size.

Setting description-width wraps labels at that width instead, so the
length of a description no longer decides how large the diagram is
drawn. Values wrap at the same right edge as the description they belong
to, and the option composes with left-labels, force-descs-on-side and
ltr-bits.

Wrapping means a label is no longer one line tall, so labels can no
longer be spaced by a fixed line height. Each is now offset by the
height it actually occupies, measured before it is placed, which is why
render gained a context block.

The option defaults to none, which keeps the single-line behaviour on
the original code paths. With it unset every diagram in the gallery
renders byte-identical to before.

CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## [Unreleased]
+- Added `description-width` config option, wrapping descriptions and values instead of drawing them on a single line
+
+## [v0.3.1] - 2026-06-14
+- Support for non-consecutive ranges ([#13](https://git.kb28.ch/HEL/rivet-typst/pulls/13))
+- Prevent drawing separators on starting lines of fields ([#17](https://git.kb28.ch/HEL/rivet-typst/pulls/17))
+- Fix end line on non-consecutive ranges ending at the highest bit not being draw ([#18](https://git.kb28.ch/HEL/rivet-typst/pulls/18))
+- Add documentation for `start` property of structures ([61f13df815f](https://git.kb28.ch/HEL/rivet-typst/commit/6f13df815f99fd6be8b6b3a02b4d53bcc8fe0aff))
+
 ## [v0.3.0] - 2025-05-03
 - updated CeTZ to 0.3.4
 - updated to Typst 0.13.1

README.md

@@ -9,7 +9,7 @@ It is based on the [homonymous Python script](https://git.kb28.ch/HEL/rivet/)
   <tr>
     <td>
       <a href="./gallery/example1.typ">
-        <img src="./gallery/example1.png" width="1000px">
+        <img src="./gallery/example1.png" width="1000px" alt="A black on white diagram showing the bit structure of a machine instruction, detailing operands, flags and selectors.">
       </a>
     </td>
   </tr>
@@ -19,7 +19,7 @@ It is based on the [homonymous Python script](https://git.kb28.ch/HEL/rivet/)
   <tr>
     <td>
       <a href="./gallery/example2.typ">
-        <img src="./gallery/example2.png" width="1000px">
+        <img src="./gallery/example2.png" width="1000px" alt="A white on blue diagram showing the bit structure of RISC-V memory instructions, detailing operands, flags and selectors.">
       </a>
     </td>
   </tr>
@@ -35,7 +35,7 @@ For more information, see the [manual](manual.pdf)
 
 To use this package, simply import `schema` from [rivet](https://typst.app/universe/package/rivet) and call `schema.load` to parse a schema description. Then use `schema.render` to render it, et voilà !
 ```typ
-#import "@preview/rivet:0.3.0": schema
+#import "@preview/rivet:0.3.1": schema
 #let doc = schema.load(yaml("path/to/schema.yaml"))
 #schema.render(doc)
 ```

docs/config.typ

@@ -26,6 +26,7 @@
 /// - full-page (bool): If true, the page will be resized to fit the diagram and take the background color
 /// - all-bit-i (bool): If true, all bit indices will be rendered, otherwise, only the ends of each range will be displayed
 /// - ltr-bits (bool): If true, bits are placed with the LSB on the left instead of the right
+/// - description-width (float | none): If set, descriptions and values wrap at this width instead of being drawn on a single line
 /// -> dictionary
 #let config(
   default-font-family: "Ubuntu Mono",
@@ -53,7 +54,8 @@
   height: 800,
   full-page: false,
   all-bit-i: true,
-  ltr-bits: false
+  ltr-bits: false,
+  description-width: none
 ) = {}
 
 /// Dark theme config

gallery/example1.typ

@@ -1,6 +1,6 @@
-#import "../src/lib.typ": schema, config
+#import "@preview/rivet:0.3.1": schema, config
 
-#let example = schema.load("/gallery/example1.yaml")
+#let example = schema.load(yaml("./example1.yaml"))
 #schema.render(example, config: config.config(
   full-page: true
 ))

gallery/example2.typ

@@ -1,6 +1,6 @@
-#import "../src/lib.typ": schema, config
+#import "@preview/rivet:0.3.1": schema, config
 
-#let example = schema.load("/gallery/example2.yaml")
+#let example = schema.load(yaml("./example2.yaml"))
 #schema.render(example, config: config.blueprint(
   full-page: true,
   left-labels: true

gallery/example3.typ

@@ -1,6 +1,6 @@
-#import "../src/lib.typ": schema, config
+#import "@preview/rivet:0.3.1": schema, config
 
-#let example = schema.load("/gallery/example1.yaml")
+#let example = schema.load(yaml("/gallery/example1.yaml"))
 //#schema.render(example)
 
 = Chapter 1

gallery/riscv/riscv.typ

@@ -1,14 +1,14 @@
-#import "../../src/lib.typ": *
+#import "@preview/rivet:0.3.1": *
 
 #let conf = config.config(
   full-page: true,
   left-labels: true
 )
-#let alu = schema.load("/gallery/riscv/alu_instr.yaml")
+#let alu = schema.load(yaml("./alu_instr.yaml"))
 #schema.render(alu, config: conf)
 
-#let branch = schema.load("/gallery/riscv/branch_instr.yaml")
+#let branch = schema.load(yaml("./branch_instr.yaml"))
 #schema.render(branch, config: conf)
 
-#let mem = schema.load("/gallery/riscv/mem_instr.yaml")
+#let mem = schema.load(yaml("./mem_instr.yaml"))
 #schema.render(mem, config: conf)

gallery/test.typ

@@ -1,16 +1,17 @@
-#import "../src/lib.typ": *
+#import "@preview/rivet:0.3.1": *
 
-#let test-yaml = schema.load("/gallery/test.yaml")
+#let test-yaml = schema.load(yaml("./test.yaml"))
 #schema.render(test-yaml, config: config.config(
   full-page: true
 ))
 
-#let test-json = schema.load("/gallery/test.json")
+#let test-json = schema.load(json("./test.json"))
 #schema.render(test-json, config: config.blueprint(
   full-page: true
 ))
 
-#let test-xml = schema.load("/gallery/test.xml")
+#let test-xml-raw = schema.xml-loader.parse(xml("./test.xml").first())
+#let test-xml = schema.load(test-xml-raw)
 #schema.render(test-xml, config: config.dark(
   full-page: true
 ))

manual.typ

@@ -105,7 +105,7 @@ Since the XML format is quite different from the other, you might find it helpfu
 
 A schema contains a dictionary of structures. There must be at least one defined structure named "main".
 
-It can also optionnaly contain a "colors" dictionary. More details about this in #link(<format-colors>)[Colors]
+It can also optionally contain a "colors" dictionary. More details about this in #link(<format-colors>)[Colors]
 
 ```json
 {
@@ -203,6 +203,36 @@ For values depending on other ranges, see #link(<format-dependencies>)[Dependenc
 }
 ```
 
+=== Wrapping descriptions <format-description-width>
+
+Descriptions and values are drawn on a single line. A diagram is scaled to fit
+the width it is given, so a long description makes the whole diagram, bit cells
+and all, shrink until it fits:
+
+#let long-schema = (structures: (main: (bits: 16, ranges: (
+  "15-8": (name: "op", description: "Operation to perform on the two operands"),
+  "7-0": (
+    name: "flags",
+    description: "Flags applied to the operation, see the table below for the meaning of each bit",
+    values: ("00000001": "carry in, added to the result before the flags are evaluated")
+  )
+))))
+#let long-sch = schema.load(long-schema)
+
+#align(center, schema.render(long-sch, width: 75%))
+
+Setting the #doc-ref("config.config") option `description-width` wraps them at
+that width instead, leaving the diagram at its natural size. The width is given
+in the same units as `bit-width`, and values wrap at the same right edge as the
+description they belong to. Each label is offset by the height it actually
+occupies, so wrapping onto several lines does not make labels overlap.
+
+```typ
+schema.render(sch, config: config.config(description-width: 300))
+```
+
+#align(center, schema.render(long-sch, width: 75%, config: lib.config.config(description-width: 300)))
+
 #pagebreak(weak: true)
 
 == Dependencies <format-dependencies>
@@ -363,7 +393,7 @@ structures:
 #let x = schema.xml-loader.load("schema.xml")
 #let s = schema.load(x)
 // From file
-#let x = schema.xml-loader.parse(yaml("schema.yaml").first())
+#let x = schema.xml-loader.parse(xml("schema.xml").first())
 #let s = schema.load(x)
 // Raw block
 #let s = schema.load(```xml

src/cetz.typ

@@ -1 +0,0 @@
-#import "@preview/cetz:0.3.4": *

src/config.typ

@@ -25,6 +25,7 @@
   full-page: false,
   all-bit-i: true,
   ltr-bits: false,
+  description-width: none,
 ) = {
   return (
     default-font-family: default-font-family,
@@ -53,6 +54,7 @@
     full-page: full-page,
     all-bit-i: all-bit-i,
     ltr-bits: ltr-bits,
+    description-width: description-width,
   )
 }
 

src/lib.typ

@@ -1,4 +1,4 @@
-#let version = version(0,3,0)
+#let version = version(0,3,1)
 
 #import "config.typ"
 #import "schema.typ"

src/render/structure.typ

@@ -1,116 +0,0 @@
-#import "../cetz.typ": draw
-
-#let BACKGROUND-LAYER = -1
-
-#let draw-track(config, schema, struct, pos) = draw.group(name: "track", {
-  let colors = schema.at("colors", default: (:))
-  let total-width = struct.bits * config.bit-width
-
-  let bit-colors = (:)
-
-  if struct.name in colors {
-    for (s, col) in colors.at(struct.name) {
-      let (start, end) = rng.parse-span(s)
-      for i in range(start, end + 1) {
-        bit-colors.insert(str(i), col)
-      }
-    }
-  }
-
-  let boundaries = ()
-  for r in struct.ranges.values() {
-    boundaries.push(if config.ltr-bits {r.end} else {r.start})
-    boundaries.push(if config.ltr-bits {r.start - 1} else {r.end + 1})
-  }
-
-  draw.group(name: "bits", {
-    for i in range(struct.bits) {
-      let rank = struct.start + i
-      let j = if config.ltr-bits {i} else {struct.bits - i - 1}
-      let col = bit-colors.at(str(rank), default: config.background)
-
-      // Background color
-      draw.on-layer(BACKGROUND-LAYER, {
-        draw.rect(
-          (rel: (j * config.bit-width, 0), to: pos),
-          (rel: (config.bit-width, config.bit-height)),
-          fill: col,
-          stroke: none,
-          name: str(rank)
-        )
-      })
-
-      if j != struct.bits - 1 {
-        let top = str(rank) + ".north-east"
-        let bottom = str(rank) + ".south-east"
-
-        // Group boundary
-        if rank in boundaries {
-          draw.line(
-            top,
-            bottom,
-            stroke: config.border-color
-          )
-        
-        // Bit separator
-        } else {
-          draw.line(
-            top,
-            ((), 20%, bottom),
-            stroke: config.border-color
-          )
-          draw.line(
-            bottom,
-            ((), 20%, top),
-            stroke: config.border-color
-          )
-        }
-      }
-    }
-  })
-
-  // Frame
-  draw.rect(
-    "bits.north-west", "bits.south-east",
-    name: "frame",
-    stroke: config.border-color + 2pt
-  )
-
-  // Names
-  for r in struct.ranges.values() {
-    let i0 = r.start
-    let i1 = r.end
-    if not config.ltr-bits {
-      (i0, i1) = (i1, i0)
-    }
-    let start = "bits." + str(i0) + ".north-west"
-    let end = "bits." + str(i1) + ".south-east"
-    draw.content(
-      (start, 50%, end),
-      r.name
-    )
-  }
-
-  let indices = if config.all-bit-i {
-    range(struct.start, struct.start + struct.bits)
-  } else {
-    struct.ranges.values().map(r => (r.start, r.end)).flatten().dedup()
-  }
-  for i in indices {
-    draw.content(
-      "bits." + str(i) + ".north",
-      anchor: "south",
-      str(i),
-      padding: 4pt  // TODO: Maybe configurable
-    )
-  }
-})
-
-#let render(
-  config,
-  schema,
-  struct,
-  pos: (0, 0),
-) = draw.group(name: struct.name, {
-  draw-track(config, schema, struct, pos)
-})

src/renderer.typ

@@ -1,10 +1,650 @@
-#import "cetz.typ": canvas
-#import "render/structure.typ" as struct
+#import "@preview/cetz:0.3.4": canvas, draw
 
-#let render(config, schema, width: 100%) = {
-  canvas(length: 1pt, {
-    struct.render(config, schema, schema.structures.main)
+#import "range.typ" as rng
+#import "structure.typ"
+#import "vec.typ"
+
+#let draw-rect(color, x, y, width, height, thickness: 0) = {
+  let fill = none
+  let stroke = color + thickness * 1pt
+  if thickness == 0 {
+    fill = color
+    stroke = none
+  }
+  draw.rect((x, -y), (x + width, -y - height), fill: fill, stroke: stroke)
+}
+
+#let draw-text(
+  txt,
+  color,
+  x,
+  y,
+  anchor: "center",
+  font: none,
+  italic: false,
+  size: 1em,
+  fill: none
+) = {
+  let text-params = (:)
+  if font != none {
+    text-params.insert("font", font)
+  }
+  if italic {
+    text-params.insert("style", "italic")
+  }
+
+  draw.content(
+    (x, -y),
+    text(txt, fill: color, size: size, ..text-params),
+    anchor: anchor,
+    stroke: none
+  )
+}
+
+// A wrapped label is built as plain content so that its height can be measured
+// before it is placed, and the label after it offset by what it really takes.
+#let text-block(txt, color, width, font: none, italic: false, size: 1em) = {
+  let text-params = (:)
+  if font != none {
+    text-params.insert("font", font)
+  }
+  if italic {
+    text-params.insert("style", "italic")
+  }
+
+  box(width: width * 1pt, text(txt, fill: color, size: size, ..text-params))
+}
+
+#let draw-block(block, x, y) = {
+  draw.content((x, -y), block, anchor: "north-west", stroke: none)
+}
+
+#let draw-line(color, a, b) = {
+  let (x0, y0) = a
+  let (x1, y1) = b
+  draw.line((x0, -y0), (x1, -y1), stroke: color)
+}
+
+#let draw-lines(color, ..pts) = {
+  let pts = pts.pos().map(pt => (pt.at(0), -pt.at(1)))
+  draw.line(..pts, stroke: color)
+}
+
+#let draw-poly(color, ..pts, thickness: 0) = {
+  let pts = pts.pos().map(pt => (pt.at(0), -pt.at(1)))
+  let params = (
+    stroke: (paint: color, thickness: thickness),
+    fill: none
+  )
+  if thickness == 0 {
+    params = (
+      stroke: none,
+      fill: color
+    )
+  }
+  draw.line(..pts, ..params)
+}
+
+#let draw-underbracket(config, start, end, bits-y) = {
+  let bit-w = config.bit-width
+  let bit-h = config.bit-height
+
+  let x0 = start + bit-w / 2
+  let x1 = end - bit-w / 2
+  let y0 = bits-y + bit-h * 1.25
+  let y1 = bits-y + bit-h * 1.5
+
+  let col = config.link-color
+  draw-lines(col, (x0, y0), (x0, y1), (x1, y1), (x1, y0))
+}
+
+#let draw-link(
+  config,
+  start-x,
+  start-y,
+  end-x,
+  end-y
+) = {
+  let bit-h = config.bit-height
+  let arrow-margin = config.arrow-margin
+
+  if end-x > start-x {
+    end-x -= arrow-margin
+  } else {
+    end-x += arrow-margin
+  }
+
+  draw-lines(
+    config.link-color,
+    (start-x, start-y + bit-h * 1.5),
+    (start-x, end-y + bit-h / 2),
+    (end-x, end-y + bit-h / 2),
+  )
+}
+
+#let draw-values(config, values, desc-x, desc-y) = {
+  let shapes = ()
+  let txt-col = config.text-color
+  let bit-w = config.bit-height  // Why ? I don't remember
+  let gap = config.values-gap
+
+  for (val, desc) in values.pairs().sorted(key: p => p.first()) {
+    desc-y += gap
+    let txt = val + " = " + desc
+    if config.description-width == none {
+      shapes += draw-text(
+        txt, txt-col, desc-x + bit-w / 2, desc-y,
+        anchor: "north-west",
+        font: config.italic-font-family,
+        italic: true,
+        size: config.italic-font-size
+      )
+
+      desc-y += config.italic-font-size / 1.2pt
+    } else {
+      let block = text-block(
+        txt, txt-col, config.description-width - bit-w / 2,
+        font: config.italic-font-family,
+        italic: true,
+        size: config.italic-font-size
+      )
+      shapes += draw-block(block, desc-x + bit-w / 2, desc-y)
+      desc-y += measure(block).height.pt()
+    }
+  }
+
+  return (shapes, desc-x, desc-y)
+}
+
+#let draw-description(
+  config,
+  range_,
+  start-x,
+  start-y,
+  width,
+  desc-x,
+  desc-y
+) = {
+  let shapes = ()
+  let bit-w = config.bit-width
+  let bit-h = config.bit-height
+
+  if config.left-labels {
+    desc-x = calc.min(desc-x, start-x + width / 2 - bit-w)
+  } else {
+    desc-x = calc.max(desc-x, start-x + width / 2 + bit-w)
+  }
+
+  shapes += draw-underbracket(config, start-x, start-x + width, start-y)
+
+  let mid-x = start-x + width / 2
+  let link-y = if config.description-width == none {
+    desc-y
+  } else {
+    // wrapped labels hang from desc-y, so aim at the middle of their first line
+    desc-y + config.default-font-size.pt() / 2 - bit-h / 2
+  }
+  shapes += draw-link(config, mid-x, start-y, desc-x, link-y)
+
+  let txt-x = desc-x
+
+  if config.left-labels {
+    // desc-x is the right edge of the label when they are on the left, so shift
+    // to its left edge: exactly the box width when wrapping, an estimate from
+    // the character count otherwise
+    txt-x -= if config.description-width == none {
+      range_.description.len() * config.default-font-size / 2pt
+    } else {
+      config.description-width
+    }
+  }
+
+  if config.description-width == none {
+    shapes += draw-text(
+      range_.description,
+      config.text-color,
+      txt-x, desc-y + bit-h / 2,
+      anchor: "west"
+    )
+
+    desc-y += config.default-font-size / 0.75pt
+  } else {
+    let block = text-block(
+      range_.description,
+      config.text-color,
+      config.description-width,
+      font: config.default-font-family,
+      size: config.default-font-size
+    )
+    shapes += draw-block(block, txt-x, desc-y)
+    desc-y += measure(block).height.pt()
+  }
+
+  if range_.values != none and range_.depends-on == none {
+    let shapes_
+    (shapes_, _, desc-y) = draw-values(config, range_.values, txt-x, desc-y)
+    shapes += shapes_
+  }
+
+  desc-y += config.description-margin
+
+  return (shapes, desc-x, desc-y)
+}
+
+#let draw-arrow(config, start-x, start-y, end-x, end-y, label: "") = {
+  let shapes = ()
+  let dash-len = config.dash-length
+  let dash-space = config.dash-space
+  let arrow-size = config.arrow-size
+  let link-col = config.link-color
+  let txt-col = config.text-color
+  let arrow-label-dist = config.arrow-label-distance
+
+  let start = vec.vec(start-x, start-y)
+  let end = vec.vec(end-x, end-y)
+  let start-end = vec.sub(end, start)
+  let d = vec.normalize(start-end)
+
+  let dashes = int(vec.mag(start-end) / (dash-len + dash-space))
+
+  for i in range(dashes) {
+    let a = vec.add(
+      start,
+      vec.mul(d, i * (dash-len + dash-space))
+    )
+    let b = vec.add(
+      a,
+      vec.mul(d, dash-len)
+    )
+
+    shapes += draw-line(link-col, (a.x, a.y), (b.x, b.y))
+  }
+
+  let n = vec.vec(d.y, -d.x)
+  let width = arrow-size / 1.5
+  let p1 = vec.sub(
+    end,
+    vec.sub(
+      vec.mul(d, arrow-size),
+      vec.mul(n, width)
+    )
+  )
+  let p2 = vec.sub(
+    end,
+    vec.add(
+      vec.mul(d, arrow-size),
+      vec.mul(n, width)
+    )
+  )
+
+  shapes += draw-poly(
+    link-col,
+    (end.x, end.y),
+    (p1.x, p1.y),
+    (p2.x, p2.y)
+  )
+
+  if label != "" {
+    shapes += draw-text(
+      label,
+      txt-col,
+      (start.x + end.x) / 2,
+      (start.y + end.y) / 2 + arrow-label-dist,
+      anchor: "north"
+    )
+  }
+
+  return shapes
+}
+
+#let draw-dependency(
+  draw-struct, config,
+  struct, schema, bits-x, bits-y, range_, desc-x, desc-y
+) = {
+  let shapes = ()
+
+  let bit-w = config.bit-width
+  let bit-h = config.bit-height
+  let arrow-margin = config.arrow-margin
+
+  let to-real-i(i) = {
+    return if config.ltr-bits {
+      i
+    } else {
+      struct.bits - i - 1
+    }
+  }
+
+  let start-i = to-real-i(if config.ltr-bits {range_.start} else {range_.end})
+  let start-x = bits-x + start-i * bit-w
+  let width = rng.bits(range_) * bit-w
+
+  shapes += draw-underbracket(config, start-x, start-x + width, bits-y)
+  let depend-key = rng.key(..range_.depends-on)
+  let depend-range = struct.ranges.at(depend-key)
+  let prev-range-y = bits-y + bit-h * 1.5
+
+  let prev-depend-y = if depend-range.last-value-y == -1 {
+    bits-y + bit-h * 1.5
+  } else {
+    depend-range.last-value-y
+  }
+
+  let depend-start-i = to-real-i(depend-range.end)
+  let depend-start-x = bits-x + depend-start-i * bit-w
+  let depend-width = rng.bits(depend-range) * bit-w
+  let depend-mid = depend-start-x + depend-width / 2
+  shapes += draw-underbracket(config, depend-start-x, depend-start-x + depend-width, bits-y)
+
+  for (val, data) in range_.values.pairs().sorted(key: p => p.first()) {
+    shapes += draw-arrow(config, depend-mid, prev-depend-y, depend-mid, desc-y - arrow-margin)
+
+    let val-ranges = (:)
+    for i in range(rng.bits(depend-range)) {
+      val-ranges.insert(
+        str(depend-range.end - i),
+        (name: val.at(i))
+      )
+    }
+
+    let val-struct = (
+      bits: rng.bits(depend-range),
+      start: depend-range.start,
+      ranges: val-ranges
+    )
+    val-struct = structure.load("", val-struct)
+
+    let shapes_
+    (shapes_, ..) = draw-struct(config, val-struct, schema, ox: depend-start-x, oy: desc-y)
+    shapes += shapes_
+
+    let y = desc-y + bit-h * 1.5
+
+    let x1
+    let x2
+
+    // Arrow from left to right
+    let i1 = to-real-i(range_.start)
+    let i2 = to-real-i(depend-range.end)
+    if i2 < i1 {
+      x1 = depend-start-x + depend-width + arrow-margin
+      x2 = start-x - arrow-margin
+    
+    // Arrow from right to left
+    } else {
+      x1 = depend-start-x - arrow-margin
+      x2 = start-x + width + arrow-margin
+    }
+
+    shapes += draw-arrow(config, x1, y, x2, y, label: data.description)
+    shapes += draw-arrow(config,
+      start-x + width - bit-w,
+      prev-range-y,
+      start-x + width - bit-w,
+      desc-y + bit-h - arrow-margin
+    )
+
+    prev-depend-y = desc-y + bit-h * 2 + arrow-margin
+    prev-range-y = prev-depend-y
+    depend-range.last-value-y = prev-depend-y
+
+    (shapes_, desc-y) = draw-struct(config, schema.structures.at(data.structure), schema, ox: start-x, oy: desc-y)
+    shapes += shapes_
+  }
+
+  struct.ranges.at(depend-key) = depend-range
+
+  return (shapes, desc-x, desc-y, struct)
+}
+
+#let draw-structure(config, struct, schema, ox: 0, oy: 0) = {
+  let shapes
+  let colors = schema.at("colors", default: (:))
+  let bg-col = config.background
+  let txt-col = config.text-color
+  let border-col = config.border-color
+  let bit-w = config.bit-width
+  let bit-h = config.bit-height
+
+  let (bits-x, bits-y) = (ox, oy + bit-h)
+  let bits-width = struct.bits * bit-w
+  let start-bit = struct.start
+  let bit-colors = (:)
+
+  let to-real-i(i) = {
+    return if config.ltr-bits {
+      i - start-bit
+    } else {
+      struct.bits - i - 1 + start-bit
+    }
+  }
+
+  let to-bit-i(real-i) = {
+    return if config.ltr-bits {
+      real-i + start-bit
+    } else {
+      struct.bits - real-i - 1 + start-bit
+    }
+  }
+
+  for i in range(struct.bits) {
+    bit-colors.insert(str(i), bg-col)
+  }
+  if struct.name in colors {
+    for (s, col) in colors.at(struct.name) {
+      let (start, end) = rng.parse-span(s)
+      for i in range(start, end + 1) {
+        let real-i = to-real-i(i)
+        bit-colors.insert(str(real-i), col)
+      }
+    }
+  }
+  let range-boundaries = ()
+  for r in struct.ranges.values() {
+    let start-i = to-real-i(if config.ltr-bits {r.start} else {r.end})
+    let end-i = to-real-i(if config.ltr-bits {r.end} else {r.start}) + 1
+    range-boundaries.push(start-i)
+    range-boundaries.push(end-i)
+  }
+
+  // Draw colors
+  for i in range(struct.bits) {
+    let bit-x = ox + i * bit-w
+    shapes += draw-rect(bit-colors.at(str(i)), bit-x, bits-y, bit-w+1, bit-h)
+  }
+
+  // Draw rectangle around structure
+  shapes += draw-rect(border-col, bits-x, bits-y, bits-width, bit-h, thickness: 2)
+
+  let indices = range(struct.start, struct.start + struct.bits)
+  if not config.all-bit-i {
+    indices = ()
+    for r in struct.ranges.values() {
+      indices.push(r.start)
+      indices.push(r.end)
+    }
+    // ensure first and last bits are included
+    if not indices.contains(0) { indices.insert(0, struct.start) }
+    if not indices.contains(struct.bits + struct.start - 1) {
+      indices.push(struct.bits + struct.start - 1)
+    }
+  }
+
+  for i in range(struct.bits) {
+    let bit-x = ox + i * bit-w
+    let bit-i = to-bit-i(i)
+
+    if bit-i in indices {
+      shapes += draw-text(
+        str(bit-i),
+        txt-col,
+        bit-x + bit-w / 2,
+        oy + bit-h / 2 
+      )
+    }
+
+    // Draw separator
+    if i != 0 and not i in range-boundaries {
+      shapes += draw-line(border-col, (bit-x, bits-y), (bit-x, bits-y + bit-h * 0.2))
+      shapes += draw-line(border-col, (bit-x, bits-y + bit-h * 0.8), (bit-x, bits-y + bit-h))
+    }
+  }
+
+  let ranges = structure.get-sorted-ranges(struct)
+  if config.ltr-bits {
+    ranges = ranges.rev()
+  }
+  if config.left-labels {
+    ranges = ranges.rev()
+  }
+
+  let desc-x
+  if config.force-descs-on-side {
+    desc-x = config.margins.at(3) + schema.structures.main.bits * bit-w
+    if config.left-labels {
+      desc-x = config.width - desc-x
+    }
+  } else {
+    desc-x = ox
+    if config.left-labels {
+      desc-x += struct.bits * bit-w
+    }
+  }
+
+  let desc-y = bits-y + bit-h * 2
+
+  // Names + simple descriptions
+  for (i, range_) in ranges.enumerate() {
+    let start-i = to-real-i(if config.ltr-bits {range_.start} else {range_.end})
+    let end-i = to-real-i(if config.ltr-bits {range_.end} else {range_.start})
+    let start-x = bits-x + start-i * bit-w
+    let width = rng.bits(range_) * bit-w
+
+    let name-x = start-x + width / 2
+    let name-y = bits-y + bit-h / 2
+
+    let line-x = if config.ltr-bits {start-x + width} else {start-x}
+    shapes += draw-line(border-col, (line-x, bits-y), (line-x, bits-y + bit-h))
+    shapes += draw-text(range_.name, txt-col, name-x, name-y, fill: bg-col)
+
+    // paint end line only if needed
+    let is-not-limit = if config.ltr-bits { start-i != 0 } else { end-i != struct.bits - 1 }
+    if (
+        is-not-limit
+        and ranges
+          .at(
+            i
+              + {
+                if config.ltr-bits and i < ranges.len() - 1 { 1 } else { -1 }
+              },
+          )
+          .end
+          != range_.start - 1
+    ) {
+      line-x += if config.ltr-bits { -width } else { width }
+      shapes += draw-line(
+        border-col,
+        (line-x, bits-y),
+        (line-x, bits-y + bit-h),
+      )
+    }
+    
+    if range_.description != "" {
+      let shapes_
+      (shapes_, desc-x, desc-y) = draw-description(
+        config, range_, start-x, bits-y, width, desc-x, desc-y
+      )
+      shapes += shapes_
+    }
+  }
+
+  // Dependencies
+  for range_ in ranges {
+    if range_.values() != none and range_.depends-on != none {
+      let shapes_
+      (shapes_, desc-x, desc-y, struct) = draw-dependency(
+        draw-structure, config,
+        struct, schema, bits-x, bits-y, range_, desc-x, desc-y,
+      )
+      shapes += shapes_
+    }
+  }
+
+  return (shapes, desc-y)
+}
+
+#let render(config, schema, width: 100%) = context {
+  set text(
+    font: config.default-font-family,
+    size: config.default-font-size
+  )
+
+  let main = schema.structures.main
+  let ox = config.margins.at(3)
+  if config.left-labels {
+    ox = config.width - ox - main.bits * config.bit-width
+  }
+
+  let params = if config.full-page {
+    (
+      width: auto,
+      height: auto,
+      fill: config.background,
+      margin: 0cm
+    )
+  } else {
+    (:)
+  }
+
+  set page(..params)
+
+  let cnvs = canvas(length: 1pt, background: config.background, {
+    let (shapes, _) = draw-structure(
+      config, main, schema,
+      ox: ox,
+      oy: config.margins.at(0)
+    )
+    // Workaround for margins
+    draw.group(name: "g", padding: config.margins, shapes)
+    draw.line(
+      "g.north-west",
+      "g.north-east",
+      "g.south-east",
+      "g.south-west",
+      stroke: none,
+      fill: none
+    )
   })
+
+  if config.full-page {
+    cnvs
+  } else {
+    layout(size => {
+      let m = measure(cnvs)
+      let w = m.width
+      let h = m.height
+      let base-w = if type(width) == ratio {
+        size.width * width
+      } else {
+        width
+      }
+      let r = if w == 0 {
+        0
+      } else {
+        base-w / w
+      }
+
+      let new-w = w * r
+      let new-h = h * r
+      r *= 100%
+
+      box(
+        width: new-w,
+        height: new-h,
+        scale(x: r, y: r, cnvs, reflow: true)
+      )
+    })
+  }
 }
 
 #let make(config) = {

src/xml-loader.typ

@@ -76,8 +76,9 @@
   }
 
   return (
-    bits: elmt.attrs.bits,
-    ranges: ranges
+    bits: int(elmt.attrs.bits),
+    ranges: ranges,
+    start: elmt.attrs.at("start", default: 0)
   )
 }
 

typst.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rivet"
-version = "0.3.0"
+version = "0.3.1"
 compiler = "0.13.1"
 repository = "https://git.kb28.ch/HEL/rivet-typst"
 entrypoint = "src/lib.typ"
@@ -9,6 +9,6 @@ authors = [
 ]
 categories = [ "visualization" ]
 license = "Apache-2.0"
-description = "Register / Instruction Visualizer & Explainer Tool with Typst, using CeTZ"
+description = "Register / Instruction Visualizer & Explainer Tool, using CeTZ"
 keywords = [ "assembly", "instruction", "binary" ]
 exclude = [ "gallery", "justfile", "docs" ]