factor/vm/cpu-x86.hpp

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namespace factor {
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#define CALLSTACK_BOTTOM(ctx) \
(ctx->callstack_seg->end - sizeof(cell) * 5)
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inline static void flush_icache(cell start, cell len) {}
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/* In the instruction sequence:
MOV EBX,...
JMP blah
the offset from the immediate operand to MOV to the instruction after
the jump is a cell for the immediate operand, 4 bytes for the JMP
destination, and one byte for the JMP opcode. */
static const fixnum xt_tail_pic_offset = 4 + 1;
static const unsigned char call_opcode = 0xe8;
static const unsigned char jmp_opcode = 0xe9;
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inline static unsigned char call_site_opcode(cell return_address) {
return *(unsigned char*)(return_address - 5);
}
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inline static void check_call_site(cell return_address) {
unsigned char opcode = call_site_opcode(return_address);
FACTOR_ASSERT(opcode == call_opcode || opcode == jmp_opcode);
(void)opcode; // suppress warning when compiling without assertions
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}
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inline static void* get_call_target(cell return_address) {
check_call_site(return_address);
return (void*)(*(int*)(return_address - 4) + return_address);
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}
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inline static void set_call_target(cell return_address, void* target) {
check_call_site(return_address);
*(int*)(return_address - 4) = (uint32_t)((cell)target - return_address);
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}
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inline static bool tail_call_site_p(cell return_address) {
switch (call_site_opcode(return_address)) {
case jmp_opcode:
return true;
case call_opcode:
return false;
default:
abort();
return false;
}
}
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inline static unsigned int fpu_status(unsigned int status) {
unsigned int r = 0;
if (status & 0x01)
r |= FP_TRAP_INVALID_OPERATION;
if (status & 0x04)
r |= FP_TRAP_ZERO_DIVIDE;
if (status & 0x08)
r |= FP_TRAP_OVERFLOW;
if (status & 0x10)
r |= FP_TRAP_UNDERFLOW;
if (status & 0x20)
r |= FP_TRAP_INEXACT;
return r;
}
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}