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Merged read-ahead support for Win32 file I/O from SDL 1.2 revision 3183

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--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%402456
This commit is contained in:
Sam Lantinga 2007-07-10 05:01:22 +00:00
parent f7d87960f4
commit 8daaa10d40
2 changed files with 79 additions and 14 deletions
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6
include/SDL_rwops.h
View file

@ -76,6 +76,12 @@ typedef struct SDL_RWops
{
int append;
void *h;
struct
{
void *data;
int size;
int left;
} buffer;
} win32io;
#endif
#ifdef HAVE_STDIO_H

81
src/file/SDL_rwops.c
View file

@ -29,7 +29,7 @@
#include "SDL_rwops.h"
#if defined(__WIN32__)
#ifdef __WIN32__
/* Functions to read/write Win32 API file pointers */
/* Will not use it on WinCE because stdio is buffered, it means
@ -43,6 +43,8 @@
#define INVALID_SET_FILE_POINTER 0xFFFFFFFF
#endif
#define READAHEAD_BUFFER_SIZE 1024
static int SDLCALL
win32_file_open(SDL_RWops * context, const char *filename, const char *mode)
{
@ -59,6 +61,15 @@ win32_file_open(SDL_RWops * context, const char *filename, const char *mode)
context->hidden.win32io.h = INVALID_HANDLE_VALUE; /* mark this as unusable */
context->hidden.win32io.buffer.data =
(char *) SDL_malloc(READAHEAD_BUFFER_SIZE);
if (!context->hidden.win32io.buffer.data) {
SDL_OutOfMemory();
return -1;
}
context->hidden.win32io.buffer.size = 0;
context->hidden.win32io.buffer.left = 0;
/* "r" = reading, file must exist */
/* "w" = writing, truncate existing, file may not exist */
/* "r+"= reading or writing, file must exist */
@ -128,6 +139,12 @@ win32_file_seek(SDL_RWops * context, int offset, int whence)
return -1;
}
/* FIXME: We may be able to satisfy the seek within buffered data */
if (whence == RW_SEEK_CUR && context->hidden.win32io.buffer.left) {
offset -= context->hidden.win32io.buffer.left;
}
context->hidden.win32io.buffer.left = 0;
switch (whence) {
case RW_SEEK_SET:
win32whence = FILE_BEGIN;
@ -155,23 +172,54 @@ win32_file_seek(SDL_RWops * context, int offset, int whence)
static int SDLCALL
win32_file_read(SDL_RWops * context, void *ptr, int size, int maxnum)
{
int total_need;
int total_read = 0;
int read_ahead;
DWORD byte_read;
int total_bytes;
DWORD byte_read, nread;
total_bytes = size * maxnum;
total_need = size * maxnum;
if (!context || context->hidden.win32io.h == INVALID_HANDLE_VALUE
|| total_bytes <= 0 || !size)
|| total_need <= 0 || !size)
return 0;
if (context->hidden.win32io.buffer.left > 0) {
void *data = (char *) context->hidden.win32io.buffer.data +
context->hidden.win32io.buffer.size -
context->hidden.win32io.buffer.left;
read_ahead = SDL_min(total_need, context->hidden.win32io.buffer.left);
SDL_memcpy(ptr, data, read_ahead);
context->hidden.win32io.buffer.left -= read_ahead;
if (read_ahead == total_need) {
return maxnum;
}
ptr = (char *) ptr + read_ahead;
total_need -= read_ahead;
total_read += read_ahead;
}
if (total_need < READAHEAD_BUFFER_SIZE) {
if (!ReadFile
(context->hidden.win32io.h, ptr, total_bytes, &byte_read, NULL)) {
(context->hidden.win32io.h, context->hidden.win32io.buffer.data,
READAHEAD_BUFFER_SIZE, &byte_read, NULL)) {
SDL_Error(SDL_EFREAD);
return 0;
}
nread = byte_read / size;
return nread;
read_ahead = SDL_min(total_need, (int) byte_read);
SDL_memcpy(ptr, context->hidden.win32io.buffer.data, read_ahead);
context->hidden.win32io.buffer.size = byte_read;
context->hidden.win32io.buffer.left = byte_read - read_ahead;
total_read += read_ahead;
} else {
if (!ReadFile
(context->hidden.win32io.h, ptr, total_need, &byte_read, NULL)) {
SDL_Error(SDL_EFREAD);
return 0;
}
total_read += byte_read;
}
return (total_read / size);
}
static int SDLCALL
win32_file_write(SDL_RWops * context, const void *ptr, int size, int num)
@ -186,10 +234,17 @@ win32_file_write(SDL_RWops * context, const void *ptr, int size, int num)
|| total_bytes <= 0 || !size)
return 0;
if (context->hidden.win32io.buffer.left) {
SetFilePointer(context->hidden.win32io.h,
-context->hidden.win32io.buffer.left, NULL,
FILE_CURRENT);
context->hidden.win32io.buffer.left = 0;
}
/* if in append mode, we must go to the EOF before write */
if (context->hidden.win32io.append) {
if (SetFilePointer(context->hidden.win32io.h, 0L, NULL, FILE_END)
== INVALID_SET_FILE_POINTER) {
if (SetFilePointer(context->hidden.win32io.h, 0L, NULL, FILE_END) ==
INVALID_SET_FILE_POINTER) {
SDL_Error(SDL_EFWRITE);
return 0;
}
@ -213,6 +268,10 @@ win32_file_close(SDL_RWops * context)
CloseHandle(context->hidden.win32io.h);
context->hidden.win32io.h = INVALID_HANDLE_VALUE; /* to be sure */
}
if (context->hidden.win32io.buffer.data) {
SDL_free(context->hidden.win32io.buffer.data);
context->hidden.win32io.buffer.data = NULL;
}
SDL_FreeRW(context);
}
return (0);