SYS_WRITE (0x05)

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A.3.22. `SYS_WRITE (0x05)`

Writes the contents of a buffer to a specified file at the current file position. The file position is specified either:

explicitly, by a SYS_SEEK
implicitly as one byte beyond the previous SYS_READ or SYS_WRITE request.

The file position is at the start of the file when the file is opened, and is lost when the file is closed.

Perform the file operation as a single action whenever possible. For example, do not split a write of 16KB into four 4KB chunks unless there is no alternative.

Entry

On entry, r1 contains a pointer to a three‑word data block:

word 1: Contains a handle for a file previously opened with SYS_OPEN.
word 2: Points to the memory containing the data to be written.
word 3: Contains the number of bytes to be written from the buffer to the file.

Return

On exit, r0 contains:

0 if the call is successful
the number of bytes that are not written, if there is an error.

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Home > Semihosting > Semihosting operations > `SYS_WRITE (0x05)`

A.3.22. SYS_WRITE (0x05)

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A.3.22. `SYS_WRITE (0x05)`