Word Unperfect - XT-Emporium

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#include "wp_layout_engine.h"
#include "wp_record_parser.h"
#include "wp_span_metrics.h"
#include "wp_record_stream.h"
#include <stddef.h>
#include <stdlib.h>

void wp_primary_buffer_bind_bytes_lifo(WpLayoutGlobals *wl, uint8_t *first, int count, uint buffer_space)
{
    if (wl == NULL) {
        return;
    }
    if (first == NULL || count <= 0) {
        wl->primary_record.word = (intptr_t)first;
        wl->record_used_bytes = 0;
    } else {
        wl->primary_record.word = (intptr_t)(first + count);
        wl->record_used_bytes = count;
    }
    wl->record_buffer_space = buffer_space;
}

void wp_secondary_buffer_bind(WpLayoutGlobals *wl, uint8_t *buffer, int initial_count, int free_space)
{
    if (wl == NULL) {
        return;
    }
    if (buffer == NULL) {
        wl->secondary_record.word = 0;
        wl->secondary_record_used_bytes = 0;
    } else {
        /* Cursor starts at the beginning of data; prepends move it down into free_space. */
        wl->secondary_record.as_secondary_p = (undefined *)(buffer + free_space);
        wl->secondary_record_used_bytes = initial_count;
    }
}

static uint16_t
wp_layout_active_unit_width(WpLayoutGlobals *wl)
{
    uint32_t scaled;
    uint16_t scale_q8;
    uint16_t unit;

    unit = (uint16_t)layout_get_active_span_total_width(wl);
    if (unit == 0U) {
        unit = 1U;
    }

    scale_q8 = wl->span_scale_q8_5039;
    if (scale_q8 == 0U || scale_q8 == 0x0100U) {
        return unit;
    }

    scaled = ((uint32_t)unit * (uint32_t)scale_q8) >> 8;
    if (scaled == 0U) {
        scaled = 1U;
    }
    if (scaled > 0xffffU) {
        scaled = 0xffffU;
    }
    return (uint16_t)scaled;
}

static bool
wp_layout_move_secondary_to_primary(WpLayoutGlobals *wl)
{
    uint8_t *bytes;
    int count;
    int i;
    uint16_t value;

    if (wl->secondary_record_used_bytes <= 0) {
        return true;
    }

    count = wl->secondary_record_used_bytes;
    bytes = (uint8_t *)malloc((size_t)count);
    if (bytes == NULL) {
        return false;
    }

    for (i = 0; i < count; ++i) {
        value = parser_consume_next_input_byte(wl);
        if (value == 0xffffU) {
            free(bytes);
            return false;
        }
        bytes[i] = (uint8_t)value;
    }

    for (i = count; i > 0; --i) {
        append_byte_to_buffer(wl, bytes[i - 1]);
    }

    free(bytes);
    return true;
}

static uint16_t
wp_layout_tab_width(uint16_t current_width, uint16_t unit_width)
{
    uint16_t tab_width;
    uint16_t next_stop;

    tab_width = (uint16_t)(unit_width * 8U);
    if (tab_width == 0U) {
        tab_width = 8U;
    }
    next_stop = (uint16_t)(((uint32_t)current_width / tab_width + 1U) * tab_width);
    return (uint16_t)(next_stop - current_width);
}

static uint16_t
wp_layout_record_width(const WpRecord *rec, uint16_t current_width, uint16_t unit_width)
{
    if (rec->type == WP_CODE_CHAR) {
        return unit_width;
    }
    if (rec->type == WP_CODE_SINGLE_BYTE && rec->code == 0x84U) {
        return wp_layout_tab_width(current_width, unit_width);
    }
    if (rec->type == WP_CODE_VARIABLE_LENGTH && rec->code == 0xc0U && rec->is_complete) {
        return unit_width;
    }
    return 0U;
}

void wp_layout_break_line(WpLayoutGlobals *wl, WpLine *line) {
    uint16_t current_width;
    uint16_t target_width;
    uint16_t unit_width;

    if (wl == NULL || line == NULL) {
        return;
    }

    target_width = (uint16_t)wl->primary_limit;
    if (target_width == 0) {
        target_width = 80;
    }

    line->width = 0;
    line->space_count = 0;
    line->is_hard_return = 0;
    line->end_offset = line->start_offset;

    if (!wp_layout_move_secondary_to_primary(wl)) {
        return;
    }

    current_width = 0;
    unit_width = wp_layout_active_unit_width(wl);

    while (wl->record_used_bytes > 0) {
        WpLayoutGlobals before_loop = *wl;
        WpRecord rec;
        uint16_t delta;

        wp_parser_consume_record(wl, &rec);
        if (rec.length == 0U) {
            wp_record_free(&rec);
            break;
        }

        if (rec.type == WP_CODE_SINGLE_BYTE && rec.code == 0x80U) {
            line->is_hard_return = true;
            line->end_offset = (uint16_t)(line->end_offset + rec.length);
            wp_record_free(&rec);
            break;
        }

        delta = wp_layout_record_width(&rec, current_width, unit_width);
        if (delta != 0U && current_width > 0U &&
            (uint32_t)current_width + (uint32_t)delta > (uint32_t)target_width) {
            *wl = before_loop;
            wp_record_free(&rec);
            break;
        }

        current_width = (uint16_t)(current_width + delta);
        line->end_offset = (uint16_t)(line->end_offset + rec.length);
        if (rec.type == WP_CODE_CHAR && rec.code == ' ') {
            line->space_count = (uint16_t)(line->space_count + 1U);
        }

        if (current_width >= target_width) {
            wp_record_free(&rec);
            break;
        }
        wp_record_free(&rec);
    }

    line->width = current_width;
}

void wp_layout_apply_justification(WpLine *line, uint16_t target_width) {
    if (line == NULL) {
        return;
    }
    if (line->justification == WP_JUSTIFY_FULL && !line->is_hard_return) {
        if (line->space_count > 0 && target_width > line->width) {
            uint16_t deficit = (uint16_t)(target_width - line->width);
            uint16_t extra_per_space = deficit / line->space_count;
            uint16_t remainder = deficit % line->space_count;
            (void)extra_per_space;
            (void)remainder;
            /* In WP 5.1, micro-spacing would distribute 'remainder' 
             * across the first few spaces. */
        }
    }
}

void wp_layout_paginate(WpLayoutGlobals *wl) {
    (void)wl;
    /* Background pagination:
     * 1. Start from the top of the document or last known good page break.
     * 2. Accumulate line heights until page height limit is reached.
     * 3. Account for Widows and Orphans (WP 5.1 feature).
     * 4. Insert/Update Soft Page breaks [SPg].
     */
}
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