ack/plat/msdos386/libsys/sys_rawread.s

#
! $Source$
! $State$
! $Revision$

#include "libsysasm.h"

! Read bytes from a file descriptor.  These routines do not do any
! translation between CRLF and LF line endings.
!
! Note that, for MS-DOS, a raw "write" request of zero bytes will truncate
! (or extend) the file to the current file position.

.define __sys_rawread
__sys_rawread:
file_handle = 1*4
write_buffer = 2*4
amount_to_read = 3*4

	mov eax, amount_to_read(esp)
	mov ecx, TRANSFER_BUFFER_SIZE
	cmp eax, ecx
	jge 2f
	mov ecx, eax
2:

	! Read from DOS into the transfer buffer.

	movb ah, 0x3f
	o16 mov dx, (transfer_buffer_ptr)
	o16 mov bx, file_handle(esp)
	call .sys_dpmidos
	jc 3f

	! Copy eax bytes out of the transfer buffer.

	movzx ecx, ax
	mov eax, write_buffer(esp)
	call .sys_cpyin

	xchg eax, ecx
	ret

3:
	! Process errors.

	push eax
	call __sys_seterrno
	pop ecx
	ret
Cut-and-paste the msdos86 libsys so the msdos386 stuff now at least builds. 2022-08-07 20:10:08 +00:00			`#`
			`! $Source$`
			`! $State$`
			`! $Revision$`

plat/msdos386: refactor, firm up, and optimize - refactor code for transfer buffer reads/writes, real mode int 0x21 calls, and assembler segment declarations - define transfer buffer size in one place - beef up error checking for transfer buffer operations (prevent buffer overflows) - also optimize such operations to transfer dword by dword where feasible 2022-08-26 17:20:56 +00:00			`#include "libsysasm.h"`
Cut-and-paste the msdos86 libsys so the msdos386 stuff now at least builds. 2022-08-07 20:10:08 +00:00
write() system calls work; start going through the libsys. 2022-08-17 20:34:06 +00:00			`! Read bytes from a file descriptor. These routines do not do any`
Cut-and-paste the msdos86 libsys so the msdos386 stuff now at least builds. 2022-08-07 20:10:08 +00:00			`! translation between CRLF and LF line endings.`
			`!`
			`! Note that, for MS-DOS, a raw "write" request of zero bytes will truncate`
			`! (or extend) the file to the current file position.`

			`.define __sys_rawread`
			`__sys_rawread:`
plat/msdos386: refactor, firm up, and optimize - refactor code for transfer buffer reads/writes, real mode int 0x21 calls, and assembler segment declarations - define transfer buffer size in one place - beef up error checking for transfer buffer operations (prevent buffer overflows) - also optimize such operations to transfer dword by dword where feasible 2022-08-26 17:20:56 +00:00			`file_handle = 1*4`
			`write_buffer = 2*4`
			`amount_to_read = 3*4`
Programs now start up and can write to the console, but crash when reading. 2022-08-17 22:24:08 +00:00
plat/msdos386: refactor, firm up, and optimize - refactor code for transfer buffer reads/writes, real mode int 0x21 calls, and assembler segment declarations - define transfer buffer size in one place - beef up error checking for transfer buffer operations (prevent buffer overflows) - also optimize such operations to transfer dword by dword where feasible 2022-08-26 17:20:56 +00:00			`mov eax, amount_to_read(esp)`
			`mov ecx, TRANSFER_BUFFER_SIZE`
Programs now start up and can write to the console, but crash when reading. 2022-08-17 22:24:08 +00:00			`cmp eax, ecx`
			`jge 2f`
			`mov ecx, eax`
			`2:`

			`! Read from DOS into the transfer buffer.`

			`movb ah, 0x3f`
			`o16 mov dx, (transfer_buffer_ptr)`
plat/msdos386: refactor, firm up, and optimize - refactor code for transfer buffer reads/writes, real mode int 0x21 calls, and assembler segment declarations - define transfer buffer size in one place - beef up error checking for transfer buffer operations (prevent buffer overflows) - also optimize such operations to transfer dword by dword where feasible 2022-08-26 17:20:56 +00:00			`o16 mov bx, file_handle(esp)`
			`call .sys_dpmidos`
			`jc 3f`

			`! Copy eax bytes out of the transfer buffer.`

			`movzx ecx, ax`
			`mov eax, write_buffer(esp)`
			`call .sys_cpyin`

			`xchg eax, ecx`
			`ret`
Simplify and fix reading and writing so they seem to work. 2022-08-18 19:21:33 +00:00
plat/msdos386: refactor, firm up, and optimize - refactor code for transfer buffer reads/writes, real mode int 0x21 calls, and assembler segment declarations - define transfer buffer size in one place - beef up error checking for transfer buffer operations (prevent buffer overflows) - also optimize such operations to transfer dword by dword where feasible 2022-08-26 17:20:56 +00:00			`3:`
Simplify and fix reading and writing so they seem to work. 2022-08-18 19:21:33 +00:00			`! Process errors.`

			`push eax`
			`call __sys_seterrno`
Most of read and write now works; filename-based operations partially work; but there's a nasty memory corruption somewhere which needs investigating. 2022-08-18 22:08:57 +00:00			`pop ecx`
Programs now start up and can write to the console, but crash when reading. 2022-08-17 22:24:08 +00:00			`ret`