mirror of
https://github.com/Interlisp/maiko.git
synced 2026-01-17 08:33:48 +00:00
Cleanup byteswap.c a bit (#154)
* Remove word_swap_longword.
This was the same as `swapx` and not used except in one place which
now uses `swapx` instead.
* Remove assembly versions of swapx, byte_swap_word, word_swap_page.
`swapx` and `byte_swap_word` were defined as:
```
extern inline const unsigned int swapx (unsigned int word)
{
asm("roll $16,%0" : "=g" (word) : "0" (word));
return(word);
}
extern inline const unsigned short byte_swap_word (unsigned short word)
{
asm("rolw $8,%0" : "=r" (word) : "0" (word));
return(word);
}
```
But the generated code from the C version is:
```
(lldb) disassemble -n swapx
ldex`swapx:
ldex[0x10002e0d0] <+0>: pushq %rbp
ldex[0x10002e0d1] <+1>: movq %rsp, %rbp
ldex[0x10002e0d4] <+4>: movl %edi, %eax
ldex[0x10002e0d6] <+6>: roll $0x10, %eax
ldex[0x10002e0d9] <+9>: popq %rbp
ldex[0x10002e0da] <+10>: retq
(lldb) disassemble -n byte_swap_word
ldex`byte_swap_word:
ldex[0x10002e0e0] <+0>: pushq %rbp
ldex[0x10002e0e1] <+1>: movq %rsp, %rbp
ldex[0x10002e0e4] <+4>: rolw $0x8, %di
ldex[0x10002e0e8] <+8>: movzwl %di, %eax
ldex[0x10002e0eb] <+11>: popq %rbp
ldex[0x10002e0ec] <+12>: retq
```
So we don't really stand to gain by re-enabling this old assembler code.
We would gain from switching to C99 or C11 and improving our
inlining.
* Remove 386 asm version of bit_reverse_region.
This is implemented in C and the code isn't actually set up to
allow using the assembler version.
This commit is contained in:
Bruce Mitchener
GitHub
parent
ca3f27db1f
commit
d717946929
@ -65,65 +65,6 @@
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/************************************************************************/
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#undef SWAP_WORDS
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#define SWAP_WORDS swapx
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extern inline const unsigned int swapx (unsigned int word)
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{
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asm("roll $16,%0" : "=g" (word) : "0" (word));
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return(word);
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}
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extern inline const unsigned int word_swap_longword (unsigned int word)
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{
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asm("roll $16,%0" : "=r" (word) : "0" (word));
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return(word);
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}
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extern inline const unsigned short byte_swap_word (unsigned short word)
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{
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asm("rolw $8,%0" : "=r" (word) : "0" (word));
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return(word);
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}
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extern inline void word_swap_page(unsigned short * page, int count)
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{
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asm volatile("\
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pushl %edi \n\
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pushl %esi \n\
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pushl %ecx \n\
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cld");
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asm volatile("\
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movl %0,%%esi // word pointer. \n\
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movl %%esi,%%edi \n\
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movl %1,%%ecx // count" : : "g" (page), "g" (count));
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asm volatile("\
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lodsl \n\
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rolw $8,%ax \n\
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roll $16,%eax \n\
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rolw $8,%ax \n\
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stosl \n\
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loop .-13 \n\
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\n\
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// epilogue. \n\
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popl %ecx \n\
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popl %esi \n\
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popl %edi \
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");
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}
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/************************************************************************/
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/* */
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/* */
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@ -65,65 +65,6 @@
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/************************************************************************/
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#undef SWAP_WORDS
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#define SWAP_WORDS swapx
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extern inline unsigned int swapx (unsigned int word)
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{
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asm("rol %0,16" : "=g" (word) : "0" (word));
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return(word);
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}
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extern inline unsigned int word_swap_longword (unsigned int word)
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{
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asm("rol %0,16" : "=r" (word) : "0" (word));
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return(word);
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}
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extern inline unsigned short byte_swap_word (unsigned short word)
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{
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asm("rol %0,8" : "=r" (word) : "0" (word));
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return(word);
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}
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extern inline void word_swap_page(unsigned short * page, int count)
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{
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asm volatile("\
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pushl edi \n\
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pushl esi \n\
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pushl ecx \n\
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cld");
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asm volatile("
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movl esi,%0 // word pointer. \n\
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movl edi,esi \n\
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movl ecx,%1 // count" : : "g" (page), "g" (count));
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asm volatile(" \
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lodsl \n\
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rol ax,8 \n\
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rol eax,16 \n\
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rol ax,8 \n\
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stosl \n\
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loop .-13 \n\
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\n\
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// epilogue. \n\
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popl ecx \n\
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popl esi \n\
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popl edi \n\
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");
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}
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/************************************************************************/
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/* */
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/* */
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@ -27,10 +27,6 @@
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#include "byteswapdefs.h"
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#if defined(ISC)
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#include "inlnPS2.h"
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#else
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/****************************************************************/
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/* */
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/* swap halves of a single 4-byte word */
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@ -49,23 +45,6 @@ unsigned short byte_swap_word(unsigned short word) {
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return (((word >> 8) & 0xff) | ((word & 0xff) << 8));
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}
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/****************************************************************/
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/* */
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/* Word-swap a 2-word integer */
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/* Does NOT byte-swap the words themselves. */
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/* */
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/****************************************************************/
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/***
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unsigned int word_swap_longword(word)
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unsigned int word;
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{
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return( ((word>>16)&0xffff)+((word&0xffff)<<16) );
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} ***/
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#ifndef I386
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#define word_swap_longword(word) (((word >> 16) & 0xffff) | ((word & 0xffff) << 16))
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#endif
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#endif /* !ISC */
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/****************************************************************/
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/* */
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/* Byte-swap a region wordcount words long */
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@ -77,7 +56,6 @@ void byte_swap_page(unsigned short *page, int wordcount) {
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for (i = 0; i < wordcount; i++) { *(page + i) = byte_swap_word(*(page + i)); }
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}
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#ifndef GCC386
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/****************************************************************/
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/* */
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/* Byte- & word-swap a region wordcount long-words long */
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@ -90,9 +68,8 @@ void word_swap_page(unsigned short *page, int longwordcount) {
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for (i = 0; i < (longwordcount + longwordcount); i++) {
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*(page + i) = byte_swap_word(*(page + i));
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}
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for (i = 0; i < longwordcount; i++) { *(longpage + i) = word_swap_longword(*(longpage + i)); }
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for (i = 0; i < longwordcount; i++) { *(longpage + i) = swapx(*(longpage + i)); }
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}
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#endif /* GCC386 */
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/****************************************************************/
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/* */
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@ -34,100 +34,6 @@
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/************************************************************************/
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/ swap the words in a long-word.
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.inline swapx,1
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movl 0(%esp),%eax
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rol $16,%eax
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.end
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/ swap the words in a long-word
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.inline word_swap_longword,1
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movl 0(%esp),%eax
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rol $16,%eax
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.end
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/swap the bytes in a 16-bit word
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.inline byte_swap_word,1
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movl 0(%esp),%eax
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rolw $8,%ax
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.end
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.inline word_swap_page,8
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movl 4(%esp),%ecx / word count into the loop counter
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movl 0(%esp),%edx / address of the block to swap
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movl 0(%edx),%eax
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rolw $8,%ax
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roll $16,%eax
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rolw $8,%ax
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movl %eax,0(%edx)
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add $4,%edx
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loop .-20
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.end
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.inline bit_reverse_region,16
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/args: (top width height rasterwidth)
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.noopt
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pushl %edi
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pushl %esi
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pushl %ebx
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movl 12(%esp),%edx /top
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movl %edx,%eax
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andl $-2,%edx
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movl %edx,12(%esp)
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andl $1,%eax
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shll $4,%eax
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addl 16(%esp),%eax /width
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movl 20(%esp),%edx /height
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/ 24(%esp) /rasterwidth, in words
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leal 31(%eax),%eax
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sarl $5,%eax
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leal (%eax,%eax),%eax
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movl %eax,16(%esp) / word wid now in width.
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cld / so we move up thru memory
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leal reversedbits,%ebx / for xlateb
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movl 12(%esp),%edi / starting init of word ptr
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sub $0,%edx
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jle .+63
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/ ..4:
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movl %edi,%esi /so both edi & esi are at start of line to swap
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movl 16(%esp),%ecx / byte count to ecx
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leal (%ecx,%ecx),%ecx
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/ ..3:
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lodsb
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xlat
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stosb
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loop .-3 / ..3
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movl 16(%esp),%ecx
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incl %ecx
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sarl $1,%ecx
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movl 12(%esp),%esi / must be into esi, then edi, to
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/ andl $-2,%edi / defeat the peephole optimizer.
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movl %esi,%edi
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/ ..5:
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lodsl
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rolw $8,%ax
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roll $16,%eax
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rolw $8,%ax
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stosl
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loop .-13 / ..5
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movl 12(%esp),%edi / word = word + rasterwidth
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addl 24(%esp),%edi
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addl 24(%esp),%edi
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movl %edi,12(%esp)
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decl %edx
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/ .L60: / at this point, starting word addr is in %edi
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jg .-59 / ..4
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popl %ebx
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popl %esi
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popl %edi
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.optim
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.end
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/////////////////////////////
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//
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// Dispatch loop speedup functions for the 386i
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