/ bidivhlp.s (emx+gcc) -- Copyright (c) 1996 by Eberhard Mattes #include .globl __bi_div_estimate .globl __bi_div_subtract .globl __bi_div_add_back .text /* This function isn't exactly that time-critical, but it can be written more elegantly in assembly language than in C. */ / _bi_word _bi_div_estimate (_bi_word *u, _bi_word v1, _bi_word v2) #define u 8(%ebp) #define v1 12(%ebp) #define v2 16(%ebp) ALIGN __bi_div_estimate: pushl %ebp movl %esp, %ebp PROFILE_FRAME pushl %ebx pushl %edi movl u, %edi movl -4(%edi), %eax /* EAX := u[-1] */ movl 0(%edi), %edx /* EDX := u[0] */ cmpl v1, %edx /* u[0] == v1? */ je Lmax /* Yes => use maximum quotient */ divl v1 /* EBX = q, EDX = r */ Lcommon:movl %edx, %ecx /* Save ECX (r) */ movl %eax, %ebx /* Save EAX (q) */ mull v2 /* EDX:EAX := v2 * q */ ALIGN Ltest: cmpl %ecx, %edx jb Ldone ja Ldecr cmpl -8(%edi), %eax jbe Ldone ALIGN Ldecr: decl %ebx /* q := q - 1 */ addl v1, %ecx /* Compute new r for new q */ jc Ldone subl v2, %eax /* EDX:EAX := v2 * q */ sbbl $0, %edx jmp Ltest ALIGN Ldone: movl %ebx, %eax Lreturn:popl %edi popl %ebx leave EPILOGUE(_bi_div_estimate) ALIGN Lmax: movl %edx, %ecx /* EBX:ECX := EDX:EAX */ movl %eax, %ebx movl $-1, %eax mull %ecx subl %ebx, %eax sbbl %ecx, %edx movl %eax, %edx movl $-1, %eax jz Lcommon jmp Lreturn /* r>=b, so the test is always false */ #undef u #undef v1 #undef v2 /* This function is where _bi_div_bb() spends most of its time. */ / int _bi_div_subtract (_bi_word *u, const _bi_word *v, int n, _bi_word q) #define u 8(%ebp) #define v 12(%ebp) #define n 16(%ebp) #define q 20(%ebp) ALIGN __bi_div_subtract: pushl %ebp movl %esp, %ebp PROFILE_FRAME pushl %ebx pushl %esi pushl %edi movl u, %edi /* EDI := u */ movl v, %esi /* ESI := v */ movl n, %ecx /* ECX := n */ xorl %ebx, %ebx /* mul_carry := 0, sub_borrow := 0 */ ALIGN L1: movl (%esi), %eax leal 4(%esi), %esi mull q addl %ebx, %eax adcl $0, %edx movl %edx, %ebx subl %eax, (%edi) adcl $0, %ebx leal 4(%edi), %edi decl %ecx jnz L1 subl %ebx, (%edi) sbbl %eax, %eax popl %edi popl %esi popl %ebx leave EPILOGUE(_bi_div_subtract) #undef u #undef v #undef n #undef q /* This function isn't exactly that time-critical, but it can be written more elegantly in assembly language than in C. */ / int _bi_div_add_back (_bi_word *u, const _bi_word *v, int n) #define u 8(%ebp) #define v 12(%ebp) #define n 16(%ebp) ALIGN __bi_div_add_back: pushl %ebp movl %esp, %ebp PROFILE_FRAME pushl %esi pushl %edi movl u, %edi /* EDI := u */ movl v, %esi /* ESI := v */ movl n, %ecx /* ECX := n */ incl %ecx clc ALIGN L2: movl (%esi), %eax leal 4(%esi), %esi adcl %eax, (%edi) leal 4(%edi), %edi decl %ecx jnz L2 popl %edi popl %esi leave EPILOGUE(_bi_div_add_back)