ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

The System Level Programmers’ Model
return;
// SPSRWriteByInstr()
// ==================
if !IsSecure() && value == ‘10001’ && NSACR.RFR == ‘1’ then UNPREDICTABLE;
CPSR = value; // M mode bits
SPSRWriteByInstr(bits(32) value, bits(4) bytemask)
if CurrentModeIsUserOrSystem() then UNPREDICTABLE;
if bytemask == ‘1’ then
SPSR[] = value; // N,Z,C,V,Q flags, IT,J execution state bits
if bytemask == ‘1’ then
// bits are reserved SBZP bits
SPSR[] = value; // GE flags
if bytemask == ‘1’ then
SPSR[] = value; // IT execution state bits, E bit, A interrupt mask
if bytemask == ‘1’ then
SPSR[] = value; // I,F interrupt masks, T execution state bit
if BadMode(value) then // Mode bits
UNPREDICTABLE;
else
SPSR[] = value;
return;
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