Move stack manipulation code from util.c to new file stacks.c.

Move the threading and stack_hop code to a new file.

1 files changed, 16 insertions, 179 deletions

diff --git a/src/util.c b/src/util.c
index b1c116b..d908ed9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -6,14 +6,7 @@
 
 #include "util.h" // call16
 #include "bregs.h" // struct bregs
-#include "farptr.h" // GET_FLATPTR
-#include "biosvar.h" // get_ebda_seg
-
-static inline u32 getesp() {
-    u32 esp;
-    asm("movl %%esp, %0" : "=rm"(esp));
-    return esp;
-}
+#include "config.h" // BUILD_STACK_ADDR
 
 
 /****************************************************************
@@ -64,33 +57,6 @@ __call16_int(struct bregs *callregs, u16 offset)
     call16(callregs);
 }
 
-// Switch to the extra stack in ebda and call a function.
-inline u32
-stack_hop(u32 eax, u32 edx, u32 ecx, void *func)
-{
-    ASSERT16();
-    u16 ebda_seg = get_ebda_seg(), bkup_ss;
-    u32 bkup_esp;
-    asm volatile(
-        // Backup current %ss/%esp values.
-        "movw %%ss, %w3\n"
-        "movl %%esp, %4\n"
-        // Copy ebda seg to %ds/%ss and set %esp
-        "movw %w6, %%ds\n"
-        "movw %w6, %%ss\n"
-        "movl %5, %%esp\n"
-        // Call func
-        "calll %7\n"
-        // Restore segments and stack
-        "movw %w3, %%ds\n"
-        "movw %w3, %%ss\n"
-        "movl %4, %%esp"
-        : "+a" (eax), "+d" (edx), "+c" (ecx), "=&r" (bkup_ss), "=&r" (bkup_esp)
-        : "i" (EBDA_OFFSET_TOP_STACK), "r" (ebda_seg), "m" (*(u8*)func)
-        : "cc", "memory");
-    return eax;
-}
-
 // 16bit trampoline for enabling irqs from 32bit mode.
 ASM16(
     "  .global trampoline_checkirqs\n"
@@ -99,154 +65,25 @@ ASM16(
     "  lretw"
     );
 
-static void
-check_irqs32()
-{
-    extern void trampoline_checkirqs();
-    struct bregs br;
-    br.flags = F_IF;
-    br.code.seg = SEG_BIOS;
-    br.code.offset = (u32)&trampoline_checkirqs;
-    call16big(&br);
-}
-
-static void
-check_irqs16()
-{
-    asm volatile(
-        "sti\n"
-        "nop\n"
-        "rep ; nop\n"
-        "cli\n"
-        "cld\n"
-        : : :"memory");
-}
-
-
-/****************************************************************
- * Threads
- ****************************************************************/
-
-#define THREADSTACKSIZE 4096
-
-struct thread_info {
-    struct thread_info *next;
-    void *stackpos;
-};
-
-struct thread_info MainThread;
-
 void
-thread_setup()
-{
-    MainThread.next = &MainThread;
-    MainThread.stackpos = NULL;
-}
-
-struct thread_info *
-getCurThread()
-{
-    u32 esp = getesp();
-    if (esp <= BUILD_STACK_ADDR)
-        return &MainThread;
-    return (void*)ALIGN_DOWN(esp, THREADSTACKSIZE);
-}
-
-// Briefly permit irqs to occur.
-void
-yield()
+check_irqs()
 {
     if (MODE16) {
-        // In 16bit mode, just directly check irqs.
-        check_irqs16();
-        return;
-    }
-    if (! CONFIG_THREADS) {
-        check_irqs32();
-        return;
+        asm volatile(
+            "sti\n"
+            "nop\n"
+            "rep ; nop\n"
+            "cli\n"
+            "cld\n"
+            : : :"memory");
+    } else {
+        extern void trampoline_checkirqs();
+        struct bregs br;
+        br.flags = F_IF;
+        br.code.seg = SEG_BIOS;
+        br.code.offset = (u32)&trampoline_checkirqs;
+        call16big(&br);
     }
-    struct thread_info *cur = getCurThread();
-    if (cur == &MainThread)
-        // Permit irqs to fire
-        check_irqs32();
-
-    // Switch to the next thread
-    struct thread_info *next = cur->next;
-    asm volatile(
-        "  pushl $1f\n"                 // store return pc
-        "  pushl %%ebp\n"               // backup %ebp
-        "  movl %%esp, 4(%%eax)\n"      // cur->stackpos = %esp
-        "  movl 4(%%ecx), %%esp\n"      // %esp = next->stackpos
-        "  popl %%ebp\n"                // restore %ebp
-        "  retl\n"                      // restore pc
-        "1:\n"
-        : "+a"(cur), "+c"(next)
-        :
-        : "ebx", "edx", "esi", "edi", "cc", "memory");
-}
-
-// Last thing called from a thread (called on "next" stack).
-static void
-__end_thread(struct thread_info *old)
-{
-    struct thread_info *pos = &MainThread;
-    while (pos->next != old)
-        pos = pos->next;
-    pos->next = old->next;
-    free(old);
-    dprintf(DEBUG_thread, "\\%08x/ End thread\n", (u32)old);
-}
-
-void
-run_thread(void (*func)(void*), void *data)
-{
-    ASSERT32();
-    if (! CONFIG_THREADS)
-        goto fail;
-    struct thread_info *thread;
-    thread = memalign_tmphigh(THREADSTACKSIZE, THREADSTACKSIZE);
-    if (!thread)
-        goto fail;
-
-    thread->stackpos = (void*)thread + THREADSTACKSIZE;
-    struct thread_info *cur = getCurThread();
-    thread->next = cur->next;
-    cur->next = thread;
-
-    dprintf(DEBUG_thread, "/%08x\\ Start thread\n", (u32)thread);
-    asm volatile(
-        // Start thread
-        "  pushl $1f\n"                 // store return pc
-        "  pushl %%ebp\n"               // backup %ebp
-        "  movl %%esp, 4(%%edx)\n"      // cur->stackpos = %esp
-        "  movl 4(%%ebx), %%esp\n"      // %esp = thread->stackpos
-        "  calll *%%ecx\n"              // Call func
-
-        // End thread
-        "  movl (%%ebx), %%ecx\n"       // %ecx = thread->next
-        "  movl 4(%%ecx), %%esp\n"      // %esp = next->stackpos
-        "  movl %%ebx, %%eax\n"
-        "  calll %4\n"                  // call __end_thread(thread)
-        "  popl %%ebp\n"                // restore %ebp
-        "  retl\n"                      // restore pc
-        "1:\n"
-        : "+a"(data), "+c"(func), "+b"(thread), "+d"(cur)
-        : "m"(*(u8*)__end_thread)
-        : "esi", "edi", "cc", "memory");
-    return;
-
-fail:
-    func(data);
-}
-
-void
-wait_threads()
-{
-    ASSERT32();
-    if (! CONFIG_THREADS)
-        return;
-    while (MainThread.next != &MainThread)
-        yield();
 }