sb
Store byte
This instruction is defined by:
-
I, version >= 0
This instruction is included in the following profiles:
-
RVA20S64 (Mandatory)
-
RVA20U64 (Mandatory)
-
RVA22S64 (Mandatory)
-
RVA22U64 (Mandatory)
Synopsis
Store 8 bits of data from register rs2 to an
address formed by adding rs1 to a signed offset.
Decode Variables
Bits<12> imm = {$encoding[31:25], $encoding[11:7]};
Bits<5> rs2 = $encoding[24:20];
Bits<5> rs1 = $encoding[19:15];Execution
-
IDL
-
Sail
XReg virtual_address = X[rs1] + imm;
write_memory<8>(virtual_address, X[rs2][7:0], $encoding);{
let offset : xlenbits = sign_extend(imm);
/* Get the address, X(rs1) + offset.
Some extensions perform additional checks on address validity. */
match ext_data_get_addr(rs1, offset, Write(Data), width) {
Ext_DataAddr_Error(e) => { ext_handle_data_check_error(e); RETIRE_FAIL },
Ext_DataAddr_OK(vaddr) =>
if check_misaligned(vaddr, width)
then { handle_mem_exception(vaddr, E_SAMO_Addr_Align()); RETIRE_FAIL }
else match translateAddr(vaddr, Write(Data)) {
TR_Failure(e, _) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
TR_Address(paddr, _) => {
let eares : MemoryOpResult(unit) = match width {
BYTE => mem_write_ea(paddr, 1, aq, rl, false),
HALF => mem_write_ea(paddr, 2, aq, rl, false),
WORD => mem_write_ea(paddr, 4, aq, rl, false),
DOUBLE => mem_write_ea(paddr, 8, aq, rl, false)
};
match (eares) {
MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL },
MemValue(_) => {
let rs2_val = X(rs2);
let res : MemoryOpResult(bool) = match (width) {
BYTE => mem_write_value(paddr, 1, rs2_val[7..0], aq, rl, false),
HALF => mem_write_value(paddr, 2, rs2_val[15..0], aq, rl, false),
WORD => mem_write_value(paddr, 4, rs2_val[31..0], aq, rl, false),
DOUBLE if sizeof(xlen) >= 64
=> mem_write_value(paddr, 8, rs2_val, aq, rl, false),
_ => report_invalid_width(__FILE__, __LINE__, width, "store"),
};
match (res) {
MemValue(true) => RETIRE_SUCCESS,
MemValue(false) => internal_error(__FILE__, __LINE__, "store got false from mem_write_value"),
MemException(e) => { handle_mem_exception(vaddr, e); RETIRE_FAIL }
}
}
}
}
}
}
}