FreeCalypso > hg > freecalypso-tools
view target-utils/tf-breakin/payload.S @ 465:003e48f8ebe1
rvinterf/etmsync/fsnew.c: cast 0 to (char *) for execl sentinel
I generally don't use NULL and use plain 0 instead, based on a "NULL
considered harmful" discussion on the classiccmp mailing list many aeons
ago (I couldn't find it, and I reason that it must have been 2005 or
earlier), but a recent complaint by a packager sent me searching, and I
found this:
https://ewontfix.com/11/
While I don't give a @#$% about "modern" systems and code-nazi tools,
I realized that passing a plain 0 as a pointer sentinel in execl is wrong
because it will break on systems where pointers are longer than the plain
int type. Again, I don't give a @#$% about the abomination of x86_64 and
the like, but if anyone ever manages to port my code to something like a
PDP-11 (16-bit int, 32-bit long and pointers), then passing a plain 0
as a function argument where a pointer is expected most definitely won't
work: if the most natural stack slot and SP alignment unit is 16 bits,
fitting an int, with longs and pointers taking up two such slots, then
the call stack will be totally wrong with a plain 0 passed for a pointer.
Casting the 0 to (char *) ought to be the most kosher solution for the
most retro systems possible.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Mon, 11 Feb 2019 00:00:19 +0000 |
parents | e7502631a0f9 |
children |
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.text .org 0 @ allow entry in Thumb state .code 16 bx pc nop .code 32 @ set CPSR like mot931c payload does msr CPSR_c, #0xd3 @ disable the watchdog ldr r1, =0xfffff802 mov r0, #0xf5 strh r0, [r1, #2] mov r0, #0xa0 strh r0, [r1, #2] @ MODEM UART ldr r6, =0xffff5800 @ wait for any previous output to flush out 1: ldrb r0, [r6, #5] tst r0, #0x20 beq 1b @ send our indication adr r1, outstr mov r2, #6 1: ldrb r0, [r1], #1 strb r0, [r6] subs r2, r2, #1 bne 1b @ wait for this output to go out to the TxD pin 1: ldrb r0, [r6, #5] tst r0, #0x40 beq 1b @ enable the Calypso boot ROM ldr r1, =0xFFFFFB10 mov r2, #0x0100 strh r2, [r1] @ jump to it! mov pc, #0 .ltorg outstr: .byte 2,2,2,'O','K',2