From 72b87c985dc9324d896333f9ddaf317cece8a812 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Sun, 8 Aug 2021 16:32:38 +0100 Subject: [PATCH] data: Improve the example with a diagram And other improvements to readability. (cherry picked from commit 4e3a9bda2b7a3d141234e26250c69baa6ed5194d) --- plugins/data/nbdkit-data-plugin.pod | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/plugins/data/nbdkit-data-plugin.pod b/plugins/data/nbdkit-data-plugin.pod index 32a450ab..b69435e9 100644 --- a/plugins/data/nbdkit-data-plugin.pod +++ b/plugins/data/nbdkit-data-plugin.pod @@ -172,18 +172,24 @@ compact format. It is a string containing a list of bytes which are written into the disk image sequentially. You can move the virtual offset where bytes are written using C<@offset>. -For example: - nbdkit data '0 1 2 3 @0x1fe 0x55 0xaa' -creates a 0x200 = 512 byte (1 sector) image containing the four bytes -C<0 1 2 3> at the start, and the two bytes C<0x55 0xaa> at the end of -the sector, with the remaining 506 bytes in the middle being all -zeroes. In this example the size (512 bytes) is implied by the data. -But you could additionally use the C parameter to either -truncate or extend (with zeroes) the disk image. +creates: -Whitespace between fields in the string is ignored. + total size 0x200 = 512 bytes (1 sector) +┌──────┬──────┬──────┬──────┬───────── ── ── ───┬──────┬──────┐ +│ 0 │ 1 │ 2 │ 3 │ 0 0 ... 0 │ 0x55 │ 0xaa │ +└──────┴──────┴──────┴──────┴───────── ── ── ───┴──────┴──────┘ + ↑ + offset 0x1fe + +In this example the size is implied by the data. But you could also +use the C parameter to either truncate or extend (with zeroes) +the disk image. Another way to write the same disk would be this, +where we align the offset to the end of the sector and move back 2 +bytes to write the signature: + + nbdkit data '0 1 2 3 @^0x200 @-2 le16:0xaa55' Fields in the string can be: -- 2.31.1