// SPDX-License-Identifier: Apache-2.0
; specs/widgets/golden-gf32.t27 -- the infographic of lesson 16 of the GoldenFloat course (specs/course/goldenfloat.t27)
; Source of truth for public/widgets/golden-gf32/ (gHashTag/trinity): scripts/widget-pages-from-spec.mjs compiles
; this file, checks its constants, evaluates the tests below and writes the page. tool.js is one import of
; ../infographic.js, which draws SAY_TABLE_* as a real <table> and SAY_FLOW_* as an SVG diagram with a
; <title>, black and white, and holds no words of its own. ASCII only (L3), English only (LANG-EN).
; The lesson spec it illustrates: public/t27/files/specs/numeric/gf32.t27.
; phi^2 + 1/phi^2 = 3 | TRINITY

module widget_golden_gf32;

pub const KIND : str = "widget-tool";
pub const ID : str = "golden-gf32";
pub const TITLE : str = "GoldenFloat 16: GF32, a single";
pub const DESCRIPTION : str = "GF32: 32 bits as the spec lays them out, beside IEEE single, read from gf32.t27. Lesson 16 of the GoldenFloat course.";
pub const IMAGE_ALT : str = "A black and white table, GF32: 32 bits as the spec lays them out: Sign, 1 bit, SIGN_BITS; Exponent, 12 bits, EXP_BITS > 8, IEEE has 8; Mantissa, 19 bits, MANT_BITS < 23, IEEE has 23; Bias, 2047, EXP_BIAS = 2^(E-1) - 1; Distance from 1 / phi, 0.0135, PHI_DISTANCE.";
pub const HOOK : str = "Thirty-two bits split by phi: 1 sign, 12 exponent, 19 mantissa, bias 2047.";
pub const CATEGORY : str = "compiler";
pub const DATA_SOURCES : [2]str = ["The lesson spec public/t27/files/specs/numeric/gf32.t27, read when the course was authored; every number in the table is a constant, a test value or arithmetic of that file", "Nothing on this page was measured on hardware or timed; a value written into a test is said to be written in, not computed"];
pub const READS_LOCAL_FILES : bool = false;
pub const SENDS_NOTHING : bool = true;

; --- The table -----------------------------------------------------------------------------
pub const SAY_TABLE_CAPTION : str = "GF32: 32 bits as the spec lays them out";
pub const SAY_TABLE_HEAD : [3]str = ["Field", "Value", "Spec constant"];
pub const SAY_TABLE_CELLS : [15]str = ["Sign", "1 bit", "SIGN_BITS", "Exponent", "12 bits", "EXP_BITS > 8, IEEE has 8", "Mantissa", "19 bits", "MANT_BITS < 23, IEEE has 23", "Bias", "2047", "EXP_BIAS = 2^(E-1) - 1", "Distance from 1 / phi", "0.0135", "PHI_DISTANCE"];
pub const K_TABLE_COLS : u8 = 3;
pub const K_TABLE_ROWS : u8 = 5;
pub const K_TABLE_CELLS : u16 = 15;

; --- The diagram and the note ----------------------------------------------------------------
pub const SAY_FLOW_TITLE : str = "How GF32 gets its split";
pub const SAY_FLOW_STEPS : [3]str = ["N = 32 bits", "E = round((32 - 1) / phi^2) = 12", "M = 32 - 1 - 12 = 19"];
pub const K_FLOW_STEPS : u8 = 3;
pub const SAY_NOTE : str = "At the width of IEEE single, GF32 trades 4 mantissa bits for 4 more exponent bits.";

test the_cells_fill_whole_rows {
    assert K_TABLE_ROWS * K_TABLE_COLS == K_TABLE_CELLS;
}

test the_table_has_a_body {
    assert K_TABLE_ROWS > 0;
    assert K_TABLE_COLS > 0;
}

test the_diagram_has_every_step {
    assert K_FLOW_STEPS == 3;
    assert K_FLOW_STEPS > 1;
}