Mercurial > sdl-ios-xcode
view src/hermes/x86_main.asm @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | 3202d727bb4b |
children | 393092a3ebf6 |
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; ; x86 format converters for HERMES ; Some routines Copyright (c) 1998 Christian Nentwich (brn@eleet.mcb.at) ; This source code is licensed under the GNU LGPL ; ; Please refer to the file COPYING.LIB contained in the distribution for ; licensing conditions ; ; Most routines are (c) Glenn Fiedler (ptc@gaffer.org), used with permission ; BITS 32 GLOBAL _ConvertX86 GLOBAL _x86return GLOBAL _Hermes_X86_CPU SECTION .text ;; _ConvertX86: ;; [ESP+8] ConverterInfo* ;; -------------------------------------------------------------------------- ;; ConverterInfo (ebp+..) ;; 0: void *s_pixels ;; 4: int s_width ;; 8: int s_height ;; 12: int s_add ;; 16: void *d_pixels ;; 20: int d_width ;; 24: int d_height ;; 28: int d_add ;; 32: void (*converter_function)() ;; 36: int32 *lookup _ConvertX86: push ebp mov ebp,esp ; Save the registers used by the blitters, necessary for optimized code pusha mov eax,[ebp+8] cmp dword [eax+4],BYTE 0 je endconvert mov ebp,eax mov esi,[ebp+0] mov edi,[ebp+16] y_loop: mov ecx,[ebp+4] jmp [ebp+32] _x86return: add esi,[ebp+12] add edi,[ebp+28] dec dword [ebp+8] jnz y_loop ; Restore the registers used by the blitters, necessary for optimized code popa pop ebp endconvert: ret ;; Hermes_X86_CPU returns the CPUID flags in eax _Hermes_X86_CPU: pushfd pop eax mov ecx,eax xor eax,040000h push eax popfd pushfd pop eax xor eax,ecx jz .L1 ; Processor is 386 push ecx popfd mov eax,ecx xor eax,200000h push eax popfd pushfd pop eax xor eax,ecx je .L1 push ebx mov eax,1 cpuid mov eax,edx pop ebx .L1: ret %ifidn __OUTPUT_FORMAT__,elf section .note.GNU-stack noalloc noexec nowrite progbits %endif