Questions tagged [c]
The C programming language: its historical aspects and use on/targetting retro platforms.
75
questions
16
votes
1
answer
3k
views
In P.J. Plauger's "The Standard C Library" (1992), why are for loops used so frequently instead of while loops in the implementations?
I think I'm getting into such a specific question that there may be no answer, but it seems curious to me. This is a retrocomputing question, I promise, see the last paragraph to see how.
In Plauger's ...
- 2,197
32
votes
6
answers
5k
views
In the ISO 1990 C standard library, what was the rationale for having memcpy return one of its inputs?
The function memcpy is defined as:
void* memcpy(void* s1, void* s2, size_t n)
and the 1990 ISO standard (ISO 9899:1990) defines the function as:
Description
The memcpy function copies n characters ...
- 2,197
1
vote
0
answers
140
views
DirectX 8 Win32 GUI Not Appearing/Flickering While Running [closed]
I am programming a game with DirectX 8, and I am trying to use the GUI options that are provided by the Win32 window that I am using. However, when I try to render a button or, in this case, a textbox ...
- 169
9
votes
2
answers
549
views
Which linker or object-file format imposed the 6-character restriction on external names?
It's my understanding that the reason that external identifiers in portable C programs had (still have?) to be unique in the first six characters is that six 6-bit characters¹ fill a 36-bit machine ...
- 1,388
11
votes
3
answers
1k
views
Are there architectures with alignment greater than the size of machine word in the pre-32-bit era?
I'm writing a hobbyist cryptography project, and I want to ensure the data structures I define don't have padding bytes. The only assumption I've made about the environment, is that bytes are exactly ...
- 325
40
votes
4
answers
6k
views
When was this C function definition style, with type declarations of parameters after the parameter list, invented?
Recently I dug a little bit into old graphics libraries and found libxmi. The site was last updated on 08/09/2000. And in the source code I found the following style of function definitions which I ...
- 583
2
votes
1
answer
131
views
CC65 ignores request to correctly offset memory areas in output files
I'm trying to segment my C code into two distinct memory areas, one which will be flashed to a ROM chip and another which will end up somewhere else. Here is what I have in sbc.cfg (I was originally ...
- 123
38
votes
6
answers
7k
views
Why couldn't early C compilers handle variable declarations between statements?
In modern C, you may place variable declarations between statements:
do_something();
int x;
x = something_else();
However, older C compilers required that variables are declared before all statements:...
- 13.9k
24
votes
11
answers
10k
views
Why weren't 80s arcade games programmed in C?
I know many arcade games from the 80s were programmed in 68000 assembly. This carried on probably well into the 90s, even though Motorola C compilers existed in the 80s. Why then weren't C compilers ...
- 341
26
votes
9
answers
5k
views
How common was programming in C targeting 8-bit processors in 1983?
How often was C used to program firmware for 8-bit processors in the early 80s?
I'm reverse engineering a firmware binary for a device built around a Hitachi 6303 processor, manufactured in 1983. Even ...
- 669
14
votes
1
answer
2k
views
How can I set up the Microsoft C compiler to make it prefer immediate-mode push instructions?
I started a project to get a better understanding on how to compile a game for Windows 3.x. I tried to set up the build workflow so that it produce the byte-exact clone of a great open sourced Win16 ...
- 273
3
votes
1
answer
172
views
How to remove ___EXPORTEDSTUB statement from a NE (Win16) program's MAP?
I started a project to get a better understanding on how to compile a game for Windows 3.x. I tried to set up the build workflow so that it produce the byte-exact clone of a great open sourced Win16 ...
- 273
-2
votes
2
answers
323
views
1980s version of printf in C [closed]
In a well-known article by Ken Thompson, ( http://users.ece.cmu.edu/~ganger/712.fall02/papers/p761-thompson.pdf )
in figure 1, that formats printf with decimal %d
printf("\t%d, \n", s[i]);
...
47
votes
3
answers
5k
views
How did varargs in C develop?
C has a feature for variadic functions, my understanding is this feature was originally a hack, relying on the simple stack-based parameter passing used by early C implementations and that some time ...
- 1,879
15
votes
1
answer
2k
views
How would old software using the SIGPIPE signal really work if it were to manage _many_ pipes?
I'm wondering what was the thinking behind having a SIGPIPE signal.
From my own experience, the first thing I do is turn off that signal (SIGIGN) and use the return value of the calls to make sure it ...
- 253
58
votes
4
answers
11k
views
Why were single quotes ('…') chosen for characters, and double quotes ("…") for strings?
In C, '' is used to denote a character, while "" is used to denote a string. Why was this syntax chosen?
I tried to research this using Wikipedia’s Timeline of Programming Languages along ...
- 633
2
votes
1
answer
194
views
Where can I find the software for "DESIGN: a program to create data entry programs" by J. Michael Wuerth?
I have a copy of the book, DESIGN: a program to create data entry programs by J. Michael Wuerth.
Does anyone know where I can obtain a copy of the accompanying software for the book?
- 21
9
votes
1
answer
533
views
Which pre-ANSI C compilers allowed a conditional expression as Lvalue?
Soon after learning the C language in the late 80s, before an ANSI C compiler was available on the machines I was using, it occurred to me to check if the following compiles
int a, b, c;
foo() {
(...
- 15.8k
1
vote
1
answer
344
views
Did DEMOS have a C compiler?
DEMOS was a Soviet operating system derived from BSD Unix. The answer to this question shows that the familiar, English-derived BSD commands were essentially the same in DEMOS.
Did DEMOS have a C ...
- 13.9k
2
votes
1
answer
313
views
Microsoft C 6, far pointer, cast to int, warning C4047
Trying to access one byte in memory using segment/offset, like this
union REGS in, out;
struct SEGS segs;
int v;
char _far* p;
...
int86x(...,&in,&out,&segs);
p = (segs.es << 16) + ...
- 1,811
26
votes
1
answer
4k
views
Where is the ancient preprocessor?
I found the old C compiler from V6, and, though it seems to the modern eye a little different from good, idiomatic C, evidently it uses things like #include and #define, but I do not see how it ...
- 34.3k
1
vote
1
answer
216
views
When did cross-platform C start assuming function prototypes? [closed]
The most important difference between the original 'K&R' C, and ANSI/ISO C89/90, was function prototypes. These started being supported by some compilers in the mid-eighties, were formally ...
- 49.3k
36
votes
6
answers
5k
views
Why is this gcd implementation from the 80s so complicated?
First of all, I hope this is the right place to post this question. I was looking through one of my dad's old programming books from the 80s, and at the back it has a list of utility functions, one of ...
- 463
31
votes
3
answers
4k
views
Why is the ‘auto’ storage class specifier included in C?
The auto keyword in C seems quite redundant: wherever it makes sense to define a variable with automatic storage duration, it is already the default, so there is no reason to use the keyword. The ...
- 16.6k
14
votes
2
answers
2k
views
How would I reliably detect the amount of RAM, including Fast RAM?
If I was to write an Amiga game, what would be the best/most reliable way to detect how much RAM is actually available?
Looking at Action's Guide to AGA-Fixing!, he mentions Faulty Memory Detection:
...
- 525
7
votes
2
answers
647
views
Labels in cc65 inline assembler with #define macro
In general, it is possible to use inline assembler statements within C macros, for example
#define toscreencode(C) (__AX__ = (C), \
asm("cmp #$60"),\
...
- 4,080
11
votes
3
answers
2k
views
Is this the reason why fread/fwrite has 2 `size_t` arguments?
It just came to me that, the C standard I/O functions fread and fwrite are having 2 size_t arguments because of I guess possibly, that on some systems, there may be more memory of which whose size can ...
- 325
19
votes
10
answers
7k
views
When if ever was the C language 'int' size altered from the host machine word (register) size into a literal 32 bit size?
From the earliest K&R reference manuals I read, 'int' was synonymous with machine word and it seemed to raise adverse reactions in various user domains. With the UNIX crowd, they minimally ...
- 389
2
votes
2
answers
253
views
Why isn't this invocation of XMS function Move EMB 0Bh in Turbo C correct?
Following on from my last question, I cannot get Move Extended Memory Block (Function 0Bh) working in Turbo C 2.01.
The following main.c contains only the minimum functions: get the XMS driver pointer,...
- 9,875
8
votes
2
answers
743
views
How can I malloc() a block that's guaranteed to lie within a single DMA segment in Turbo C 2.01?
I'm following root42's videos about DOS programming using Turbo C 2.01. I've written my own Soundblaster 1.xx driver following the Creative Labs documentation, and I'm confused about memory allocation....
- 9,875
0
votes
3
answers
298
views
Should C be regarded as an Intermediate Language? [closed]
Should C be regarded as an intermediate language on a virtual machine named PDP-11 Architecture (which have a plain memory space and stacks), like opcode to jvm, msil to dotnet, asm.js to v8, which ...
- 2,438
2
votes
0
answers
189
views
Hitting the CMS Limits of Portable Code
I wrote this arbitrary precision arithmetic utility on BSD in my postgraduate days, then after graduating ported it to DOS using TurboC. Was proud that it would do the same thing with 16bit word ...
- 389
1
vote
1
answer
268
views
Working on programming a retro z80 computer (SDCC error)
I am working on coding a driver of sorts for a Z80 based computer I am making. I am compiling with SDCC and I have been getting the following?
ASlink-Warning-Undefined Global 'data' referenced by ...
- 179
3
votes
2
answers
399
views
How to implement a 'write' function in pdp-11 / MACRO-11 / ODT using simh?
So, I'm working on a project where I'm aiming to get the first winner of the IOCCC (obfuscated c code contest) dissected down to the last detail... The program is mullender.c which you can find by ...
- 235
5
votes
1
answer
361
views
What is the format of the static libraries shipping with legacy Microsoft C for DOS?
I have installed Microsoft C 5.10 on DOS 6.22. It created a 'LIB' directory with static libraries to link against. Now I need to extract the symbols and the code for the functions from them, but can't ...
- 153
0
votes
1
answer
347
views
Do any of the open source Sinclair ZX Spectrum emulators support both TR-DOS and 3DOS?
The number of Spectrum emulators has been growing for decades now so there's quite a lot for different platforms and written in different languages.
I'm interesting in learning about two of the disk ...
- 4,350
6
votes
4
answers
834
views
C/C++ UI library similar to Visual Basic for DOS
I'm looking for a UI library that offers a similar "experience" to that provided by Microsoft's infamous, Visual Basic for DOS RAD environment.
I mean, it's such a compelling environment, ...
0
votes
4
answers
389
views
What is the earliest implementation of the stack data structure in C? [closed]
I am trying to find the source code for the earliest implementation of the stack data structure in C, but I can't find anything.
I am particularly interested in knowing if the member variables of the ...
- 31
8
votes
4
answers
2k
views
Imaging a HDD from DOS over Serial
I have recently fixed an old IBM Clone, which has an MFM hard drive. The PC booted up fine, but then I saw, that a few years back, I have deleted a few important files (probably by mistake). The ...
- 363
4
votes
2
answers
568
views
ZX Spectrum scroll waiting for user input problem
I'm trying to compile a C program with z88dk for the ZX Spectrum. Using printf(), when the text hits the bottom line of the screen on line 24 the program stops executing until a key is pressed on the ...
- 81
4
votes
5
answers
827
views
Z88DK ZX Spectrum "%f" printf not working
I'm attempting to compile a program in C for the ZX Spectrum using Z88DK.
However, I'm facing an issue when trying to use printf to print out the value of a float.
The code I'm trying to compile:
#...
- 81
13
votes
3
answers
1k
views
Memory models for assembly libraries for Turbo C
Turbo C follows the Intel Memory Model where in Tiny, Small and Compact models calling a function is near but in Medium, Large and Huge models calling a function uses far calls.
If I want to develop ...
- 325
6
votes
2
answers
352
views
Why isn't the 'restrict' keyword useful in SDCC when compiling for Z80 target? [closed]
Context
SDCC claims to support C11.
I use it to write games on Z80 target (for fun and experience).
C11 defines restrict
C11 specifies the restrict keyword on pointers, which can improve generated ...
19
votes
0
answers
1k
views
Oxford C compiler for Commodore 64
I kept one floppy from my Commodore 128 (which I used mostly in C64 mode), labelled ‘Oxford C compiler’. It is a 5.25″ floppy. Don't ask me why I kept just this one; probably because I thought I ...
- 963
11
votes
1
answer
837
views
cprintf printing invisible characters in C program on VIC 20
I want to compile and run a Hello World program in C with the cc65 compiler for an unexpanded VIC-20 model. For printing I'm using the conio.h function cprintf, since the conio implementation requires ...
- 4,080
30
votes
1
answer
3k
views
Did DOS zero out the BSS area when it loaded a program?
As an example, say we have a DOS MZ EXE file that's around 20 KiB in size. The EXE header contains the value 0x1400 at offset 0x0A indicating that the program is requesting 5,120 paragraphs (or 80 KiB)...
- 1,441
29
votes
9
answers
10k
views
How did early x86 BIOS programmers manage to program full blown TUIs given very few bytes of ROM/EPROM?
I've always wondered how so much functionality and relative luxuries(CMOS Configuration Utilities. See: https://geekprank.com/bios/ for an example) included with most popular x86 BIOSes could be ...
- 401
6
votes
3
answers
1k
views
Why is modulo operation an operator for integer types but only a function for floating-point ones?
In C, we have the % operator which finds remainder of division. But it's only applicable to integral types. For floating-point types we have to use fmod function from math.h. This makes an impression ...
- 1,285
32
votes
3
answers
8k
views
Was Dennis Ritchie being too modest in this quote about C and Pascal?
In his 1993 conference proceeding The Development of the C Language, Dennis Ritchie stated
Successors
C and even B have several direct descendants, though they do not rival Pascal in ...
- 13.9k
72
votes
5
answers
16k
views
Why did C use the arrow (->) operator instead of reusing the dot (.) operator?
In the C programming language, the syntax to access the member of a structure is
structure.member
However, a member of a structure referenced by a pointer is written as
pointer->member
...
- 13.9k