From 6d016989b0ff5f600f3bdaced1ebf443d2f32da7 Mon Sep 17 00:00:00 2001
From: Ben Bridle <ben@derelict.engineering>
Date: Fri, 11 Apr 2025 16:18:31 +1200
Subject: Add support for the CP/M CMD file module format

---
 src/formats/cmd.rs | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 src/formats/cmd.rs

(limited to 'src/formats/cmd.rs')

diff --git a/src/formats/cmd.rs b/src/formats/cmd.rs
new file mode 100644
index 0000000..2ff2097
--- /dev/null
+++ b/src/formats/cmd.rs
@@ -0,0 +1,54 @@
+// CP/M CMD format, also the TRS-80 Load Module Format (LMF)
+// https://en.wikipedia.org/wiki/CMD_file_(CP/M)
+// https://www.tim-mann.org/trs80/doc/ldosq1-4.pdf (page 43)
+use crate::*;
+
+
+pub fn format_cmd(segments: &[Segment]) -> Result<Vec<u8>, FormatError> {
+    let mut records = Vec::new();
+    let mut address;
+    for segment in segments {
+        address = segment.address;
+        for chunk in segment.words.chunks(16) {
+            records.push(data_record(chunk, address)?);
+            address += 16;
+        }
+    }
+    let start_address = segments.first().map(|s| s.address).unwrap_or(0);
+    records.push(terminating_record(start_address)?);
+
+    let mut output = String::new();
+    for record in records {
+        output.push_str(&record.to_string_plain());
+    }
+    return Ok(output.into_bytes());
+}
+
+fn data_record(words: &[Tracked<Word>], address: usize) -> Result<InhxRecord, FormatError> {
+    let Ok(address) = u16::try_from(address) else {
+        return Err(FormatError::AddressTooLarge(u16::MAX as usize, address));
+    };
+    let mut record = InhxRecord::new();
+    record.byte(0x01);
+    let data_bytes = words.len() as u8;
+    record.byte(data_bytes.wrapping_add(2));
+    record.le_double(address);
+    for word in words {
+        if word.value.width > 8 {
+            return Err(FormatError::WordTooWide(8, word.width, word.source.clone()));
+        }
+        record.byte(word.value.value as u8);
+    }
+    return Ok(record);
+}
+
+fn terminating_record(address: usize) -> Result<InhxRecord, FormatError> {
+    let Ok(address) = u16::try_from(address) else {
+        return Err(FormatError::AddressTooLarge(u16::MAX as usize, address));
+    };
+    let mut record = InhxRecord::new();
+    record.byte(0x02);
+    record.byte(0x02);
+    record.le_double(address);
+    return Ok(record);
+}
-- 
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