除非在同一文件中调用，否则功能无效

Question

所以我关注tutorial，但是在 C 中进行操作，因为程序集太笨重了。这是我在 C 中完成的第一个“真实项目”，所以这肯定是一个愚蠢的错误，或者对 C 的工作方式有一些细微差别。

无论如何，我有这段代码：

/*blink.c*/
#include "gpio.h"
#include "timer.h"
#include "morse.h"
#include "util.h"
#include "mailbox.h"
#include "gpu.h"
#include "text.h"

void blink() {
    gpio_setFunction(16, 1);

    gpio_setFor(16, 0, 0x3f0000, 1);

    gpu_makeDefaultBuffer();
    gpu_fill(0xf8ff);

    //gpio_setFor(16, 0, 0x3f0000, 1);

    unsigned int i = 0;
    while(1) {
        gpu_drawPixelBridge(i, 0, i);
        //gpu_fill(i);
        if(i >= 0xffff) {
            break;
        }
        i ++;
    }

    //gpu_drawPixel(0, 0, 0x0000);
    gpu_drawAsciiChar(0x0, 0xffff, 0x0000, 50, 10);
    gpu_drawAsciiChar(0x0, 0b0011111, 0b00000011, 0, 50);
    //gpu_drawPixel(50, 50, 0x0000);
    gpu_drawAsciiChar(0x0, 0b0011111, 0b00000011, 0, 0);
    print("Hello World!");
    gpu_drawPixelBridge(10, 10, 0xffff);
    gpu_drawPixel(100, 100, 0x0008);
    gpu_drawPixelBridge(101, 101, 0x000f);
    gpu_drawPixelBridge(102, 102, 0x0080);

    gpio_setFor(16, 0, 0x1f0000, 1);

    while(1) {
        // Stuff
    }
}

/*gpu.h*/

#ifndef H_GPUH
#define H_GPUH

#define CHARACTER_WIDTH 8
#define CHARACTER_HEIGHT 16

typedef struct {
    unsigned int pwidth;
    unsigned int pheight;
    unsigned int vwidth;
    unsigned int vheight;
    unsigned int pitch;
    unsigned int depth;
    unsigned int x;
    unsigned int y;
    void* buffer;
    unsigned int size;
} gpu_request __attribute__ ((aligned (16)));

int gpu_makeDefaultBuffer();
int gpu_makeBuffer(volatile gpu_request* req);
int gpu_fill(unsigned short colour);
int gpu_drawPixelBridge(unsigned int x, unsigned int y, unsigned short colour);
int gpu_drawPixel(unsigned int x, unsigned int y, unsigned short colour);
int gpu_drawAsciiChar(unsigned char chr, unsigned short front, unsigned short back, unsigned int ox, unsigned int oy);

#endif

/*gpu.c*/

#include "gpu.h"
#include "mailbox.h"

volatile gpu_request* gpu_buffer = 0;

const unsigned char gpu_font[];

int gpu_makeDefaultBuffer() {
    volatile gpu_request r;
    r.pwidth = 1366;
    r.pheight = 768;
    r.vwidth = 1366;
    r.vheight = 768;
    r.pitch = 0;
    r.depth = 16;
    r.x = 0;
    r.y = 0;
    r.buffer = 0;
    r.size = 0;

    gpu_makeBuffer(&r);
}

int gpu_makeBuffer(volatile gpu_request* req) {
    gpu_buffer = req;

    if(mail_write((unsigned int)req+0x40000000, 1) < 0) {
        //Write fail
        gpio_errorHang(0, 1);
        return 1;
    }

    unsigned int resp = mail_read(1);

    if(resp) {
        //Fail
        gpio_errorHang(0, 2);
        return 2;
    }
}

int gpu_fill(unsigned short colour) {
    /*unsigned int i = 0;
    while(i < /*(*_gpu_buffer).size* / 1366*768*2) {
        *(volatile unsigned short *)((*_gpu_buffer).buffer+i) = colour;
        i +=2;
    }*/
    int y = 0;
    while(y < 100) {
        y ++;
        int x = 0;
        while(x < 100) {
            x ++;
            gpu_drawPixel(x, y, colour);
        }
    }
}

int gpu_drawPixel(unsigned int x, unsigned int y, unsigned short colour) {
    unsigned int dest = (y * (*gpu_buffer).pitch) + x*2;

    *(volatile unsigned short *)((*gpu_buffer).buffer+dest) = colour;
}

int gpu_drawPixelBridge(unsigned int x, unsigned int y, unsigned short colour) {
    gpu_drawPixel(x, y, colour);
}

int gpu_drawAsciiChar(unsigned char chr, unsigned short front, unsigned short back, unsigned int ox, unsigned int oy) {
    unsigned int base = (chr*16)+((int)&gpu_font);

    unsigned int y = 0;
    while(y < 16) {
        unsigned int x = 0;
        while(x < 8) {
            if((*(unsigned char*)base >> x) & 0b1) {
                gpu_drawPixel(ox+x, oy+y, front);
            }else{
                gpu_drawPixel(ox+x, oy+y, back);
            }

            x ++;
        }
        y ++;
        base ++;
    }
}

（在这篇文章中，测试和简洁都删除了验证）

好吧，如此不一致和“古怪”将是我用来描述它是如何工作的词。目前，我认为至少有一个问题是从其所在的文件中调用drawPixel。从blink.c调用drawPixelBridge和drawAsciiCharacter一样工作，但直接从blink.c调用drawPixel似乎都不起作用（可能） ）导致任何未来的尝试失败。

我想我应该解释一下绘画是如何工作的。通常，gpu_makeBuffer使用指向gpu_request结构的指针向GPU发送“mail”。然后，GPU通过将该结构的“buffer”属性设置为指向将在屏幕上绘制的字节序列的指针来响应此操作。鉴于屏幕上的东西出现在正确的位置（尽管尺寸和间距不是我预期的），我认为这样做有效。